I mean even in your best case situations where there is a legacy of interchange and generally followed protocols almost every user in the world chooses to use one of 3 providers.
Mastodon tried to take advantage of the Elon stuff and failed because no one wants a distributed system like that. Lots of people tried it and went back to twitter.
Bluesky is only doing better because even with interoperability(is it on the fediverse? I don’t actually use any of those sites to know) most people believe it to just be a single site/source and if you mentioned fediverse they’d probably see it as a negative as they did with mastodon.
It’s a social issue not a technical one and the only ones that want it are generally those already chatting on smaller forums.
