I'm a Discord server admin and I'd love to turn this on because having more discussion of my game indexable by search engines seems like a good thing in general. For new messages it seems like there's no problem, in combination with the opt-out option. But for existing users, how am I supposed to disclose the change to people? What if people posted content in the past and wouldn't want it on Google, but aren't active anymore?

Furthermore, what if someone wants to opt-out of their messages being indexed in some Discord servers but not others? I don't see that option being available right now.