Nen is as good of a power system as Cursed Energy. Both are terrible.

Great stories can have either a bad or good power system and still be great stories. You see multiple examples of that everywhere. A good writer is still a good writer after all. I love HxH to bits and I've been a fan of it for years, but that doesn't mean that Nen or Cursed Energy as a power system is good. I will detail their similarities so that the title wouldn't be clickbait and go into each issue I have with them separately.

Both
– Have the idea of talent/innateness being the gateway to the elites.
– Utilize it as "cool ability idea" first, reasoning and logic second.
– Are restrictive, and is highly dependent on the author's skill to write a good story.

There are also other similarities that I found and don't have a problem with. This is just to highlight their similarities.
– Binding vows and limitations
– Ten/Ken/Ryuu and basic CE reinforcement
– Post-mortem nen and vengeful cursed spirits
– Simple domain and En
– Netero praying after losing an arm and Todo clapping after losing a hand

Now, one by one.

Talent and Innateness

To be honest, I don't blame them. This is lazy writing, but it's the standard in literally every single media for a reason. (If you can find a counterexample, recommend me some, because these are as scarce as .)

What I do have an issue with, though, is its overuse in JJK. If Gege wanted to make a character strong, guess what he does? Either it's "highest ce output!!!!" or "crazy ce pool even higher than gojo's!!!!" or "he learned RCT in 2 months!!!!!" It's not intelligent. It's not creative. It's just a way for cool fights and aura moments to happen for hype. Not saying that Yuta vs the Sendai colony was bad. That scene was cool as shit. It became popular and a meme for a reason. But like I said, good writers can write bad power systems.

It's less of an issue with HxH, since it's only there to limit how many powerful people there actually are in the world. It doesn't make talent the main focus. (Until Ging, of course.) If everyone possessed the same power level as Silva or Uvogin, then the powerscaling would've been even more wack that it is currently. It's common practice to do this in every single story. You see it in X-Men, Baki, The Last Airbender (the avatar), Game of Thrones/A Song of Fire and Ice (dragon riding) and literally every single Shounen for a reason.

Cool abilities first, reasoning and logic second

\"I really wanted strong sorcerers to have the ability to move in mid-air like a double jump\" … \"Also, when Higuruma banged his gavel, he was using this technique of hitting the surface of space with cursed energy. He had acquired the ability to double jump.\"

This is not a debate on whether or not this actually happens. It's very obvious once you read the manga for HxH with the succession arc and read the image above.

It's very clear that Gege creates new concepts every single time he wants to solve a problem or showcase something new to increase the stakes and not make everything a wash. If the ice cream that Gege bought that day was different, he would likely have ended up with another technique entirely different from Hollow Wicker Basket. (unlikely, but you get the point.)

If you can make random shit up on the fly and have it somehow still connected with your main premise, that doesn't tell me how good of a power system that you're making is, that tells me how good of a writer you are.

HxH's succession arc. This is the reason why I'm typing this up. There won't be huge spoilers outside of ability coverage, which is minor spoilers, so beware.

This arc destroys all previous established rules and limits that once pretended to exist. Togashi was pushing it since the Chimera Ant arc, but this one really showcases how what he does is exactly the same as JJK.

I will give 2 examples. There are a lot more, but these two are extremely egregious.

Cat's Name. It allows the user of the technique to revive after being killed by someone. If the user dies, it gets summoned, takes the killer's lifeforce, and revives the user. What Nen type is this? We don't know. What could it be? Emission is probably the most likely, seeing that Meruem was considered an "emitter " for whatever reason with his aura stealing ability. And that doesn't even explain how the user can conjure a cat (nen beast?) either.

Laplace's Demon. Now this is the real reason why I wrote this. You know how Nen is usually trained and affected by the character's personality, and JJK is a power system where your powers are given through luck by birth? It seems that Togashi was a really big fan of Gege as much as Gege was a big fan of Togashi, because Tserriednich AWOKEN to his ability ACCIDENTALLY. He didn't train for it. He barely learned Nen at all. He just received it on a silver platter. This is Higuruma but worse. And I'm not going to even talk about what the ability is. You can find that out yourself. It's bad enough that you're throwing the entire concept and uniqueness of "Nen" out the window, but the reasoning behind how Tserriednich could do this (currently) is that he's just "absurdly talented."

There are examples like this everywhere since the Chimera ant arc, like Netero having the exact same ability as Kastro, but Kastro was deemed useless, and Netero was the strongest Hunter in the verse at one point. It's crystal clear, clearer than your socks after you walked Japan barefoot that Togashi thought: 1. "This ability would be really cool" and 2. "Hmm… how do I make it fit the power system" and unlike Cursed Energy, this compromises the rules of Nen as a whole.

Restrictiveness and dependence on author's skill

I define a good power/magic system as a system where any schmuck of an author can copy it, and still write stories with it without much tweaking. If the only definition of a good power system is "whether or not a good story was written with it" instead of "how easily it could be written" then it's not very productive. We're rating power systems, not stories. If you can't take HxH's system and use it to write another story without coming off as "this is a HxH copy" then it's not a good system.

Examples of bad power systems are "superhero systems" like MHA, MCU, or DC. It's not a power system if only certain people have access to specific powers. Overlaps will always exist, of course, as you can see with JJK and HxH.

Another one is also "soft magic" as a whole. Yes, Lord of the Rings and Harry Potter are considered good stories. Yes, you can write good stories with soft magic and superhero systems. Are they good power systems? No. No one is a "soft magic genre" fan. Those don't exist. Successful soft magic is usually magic that isn't important at all to the story. And it's also much harder to write a balanced system centering on soft magic or superhero systems. You need to put at least a ton of effort to be able to pull it off.

And the last one that I have is the "immutable" magic systems. It's a hard magic with rules chained up and unchanging. This is the reason why HxH turned out that way with Tserriednich and the such. Yes, Nen allows creativity both in lore and writing with the 6 categories. But it's limited to just that. There's no way to flesh it out further. There's no outside the box thinking. (This is also why I generally dislike Brandon Sanderson's magic systems.) I know I just bashed on soft magic earlier, but immutable systems are as bad as purely soft systems. Like always, the truth lies in the middle, the gray area, like Yin and Yang.

I know I'm probably the first person to call Nen "restrictive," but it's for a reason. If you don't allow change in your magic system, then it's as good as legos that you can't take apart. You'd have to bend over backwards just to get a power like Cat's Name or Laplace's Demon, like the reasoning behind how those abilities could come to be and are feasible with the Seed Urn.

JJK sits in the sweet spot technically, with a mix of an actual power system of CE combined with innate techniques allowing for a good combination. But be honest. You can't say "I would watch JJK even if innate techniques didn't exist." It's the whole reason why it's even popular.

Now I said I didn't have an issue with binding vows. I lied. It's honestly a great concept, but it's lazy writing. You'd want your characters to be balanced anyways, so to allow for greater power, you'd have to put some restriction on them. It's why Mahoraga takes time to adapt. It's not a binding vow. If he took no time to adapt, then he would literally be unstoppable.

You see it getting abused a lot with Sukuna and his bullshit binding vows. It doesn't create tension. It didn't allow for any creativity. It's just a way for Sukuna to win. Binding vows work best when it's a narrative device with actual sacrifice. Kurapika's vow showcased his determination. Gon's vow showcased his despondence. Both reveal a human emotion in a way. Like the saying "actions speak louder than words", Kurapika saying "I hate the Troupe" would not have as much impact as him being willing to cripple his ability and to die for it if he breaks the vow.

This isn't a fault of binding vows itself, but more so with how it's used in a story, so I still consider it a good system if done well.

Since I've only given examples of "bad" power systems, I'll also give examples of good power systems in my opinion.

Magic. As in DnD magic. A.k.a high fantasy as a whole. Look there's a reason why every single fantasy anime and isekais go that route. A lot of work is already done for you in terms of how the magic works. It also allows for creativity. It's not hard enough that you can only do this or that spell, and it's soft enough to allow for "hidden magic" or "inventing new magic" that you can do. It's both flexible in how much you can bend it and rigid in how much the "usual stuff" works in a way.

Dao. Qi. Meridians. Again, a lot of stuff is already done for you. It's soft in the way that you can allow for bullshit to happen and it will still make sense. No one questions how you can generate plum blossoms with Qi. It's just what you can do. But it's also so rigid that stuff like this was considered a hard science. There were (and still are today!) people who studied Meridians and Traditional Chinese Medicine in education. Even if it's not logical in hindsight, it's still consistent and logical internally.

There's also no surprise why I didn't bring up a specific example of a series that did this. It's such a good power system that it generated its own genre separated from the original work(s). You don't get that with a random system like JJK. Even the genres that I defined here itself have their own subgenres. With Dao having Wuxia, Xianxia, and Xuanhuan (among other things) and high fantasy with mana-based systems (Frieren, Ascendance of a Bookworm), skill and rpg-based systems (Overlord, Tensura), and etc.

These types of magic systems mirror real life a lot more, which I very much like. There are hard rules for most things, but built upon underlying soft rules that we will never understand. It allows for new things to be created and discovered (antimatter, wormholes, quantum computing) while also allowing for cool stuff to happen within known preexisting rules (man on the moon, maglev, the internet)

Cursed Energy and Nen ultimately fail because they are too rigid. JJK is too reliant on innate techniques for it to be considered a good system. And if Togashi wanted to bend the rules and create fresh, overpowered abilities, he shouldn't have dug himself into a hole where Nen is an unchanging entity so he could have more freedom and flexibility with his creativity.

Just a reminder, I'm talking about POWER systems. Not world building or storytelling. They're both great in that regard. HxH more so than JJK in my opinion.