How important are reddit-style flairs for people? There’s the raised issue https://github.com/LemmyNet/lemmy/issues/317 which has it listed as a far-future, with questions as far as how to handle federation.
Personally, having at least an initial implementation done on a community level would be largely sufficient, with expansion to instance-wide being optional. The situation I’ve found most useful, personally, is sports-related groups with your favored team being your flair. This gives context to comments without constantly having to say “as a X fan”
As a mod, I use userflairs to restrict certain people from posting, which cuts down on offtopic posts. And yes people can intentionally incorrectly flair themselves, but in general they won’t do that (most rule breaking offtopic posts aren’t done intentionally, they just never read the rules).
So it’s an easy way to manage a space.