Yeah it's great if that's what you want to do. Whether it makes sense for any rando to do that is another question.
Also, a journalist in a hostile regime might be one example, but a user that posted _very_ personal things under an alt account is also another example, and I bet the latter is much more common than the former.
And no, while I'm sure LLMs can be used for stylometry in academic exercises, I don't think they'll really enable any sort of automatic mass-deanonymization of random social media accounts. But who knows, the US government probably has a bunch of new PRISM-like programs going on already, so it might happen.