We're going to need sites where 100% of contributed content is human-written

It needs to be verified. That's all. That could be by a human, but it could be by AI. The point is that any content that's written by AI might be wrong, so if you're not checking it you can't trust it. AI is pretty good at checking it's own work.

I imagine with a fan wiki (or company docs in my experience) no one bothers to put the effort in. That's probably because the rewards are for writing the content, and there's absolutely no reward for checking it's correct.