> I can say that humans aren't very good at it

You're assuming the people making accusations of posts being written by AI are from humans (which I agree are not good at making this determination). However, computers analyzing massive datasets are likely to be much better at it , and this can also be a Werewolf/Mafia/Killers-type situation where AI frequently accuses posters it believes are human, of being AI, to diminish the severity of accusations and blend in better.