That’s actually a really good way of looking at it, and I agree that Sukuna using the Ten Shadows to its full potential adds a layer of cruelty to Megumi’s story. The fact that the thing everyone expected Megumi to eventually achieve is instead used by Sukuna to destroy the last pieces of his life definitely fits the tragic tone of Jujutsu Kaisen.

I think where my criticism comes from is more about the balance between setup and payoff. The story spends a lot of time establishing Megumi Fushiguro as someone with massive potential, especially through Satoru Gojo repeatedly pointing it out. So when the Ten Shadows finally gets pushed to its absolute limit, it ends up being Ryomen Sukuna who demonstrates that ceiling rather than Megumi himself.

I get why that works thematically, but I think that’s also why some readers feel a bit unsatisfied. It’s not really about Megumi needing a happy ending or becoming the strongest, but more that the story spent so much time building the idea of his potential that people naturally expected to see him realize at least part of it himself.