it doesn't necessarily have to be web-wide. it could be a single social space which is being bombarded by llm content and is incentivized to show users what is or is not verified without losing the informal culture of usernames vs. actual names.

I'd say its not all too different from what X did. But there are different technologies at play now. In any case the actual content of your text these days acts already as a kind of signature of llm vs. human made. So this is just codifying it.