I still see lots of different emails out there, outlook/hotmail is still huge, yahoo occasionally, icloud in the US.
Among my techy friend circle all of us have either our own self hosted mail, a ‘privacy’ company email, or something in the middle.
All to say, I don’t think it’s that uphill of a battle for the very large percentage of Internet users to accept the way federation works.
In my experience these “containment” boards/servers/sections tend not to work.
Long term it basically just creates a place that attracts those you don’t want, and becomes place for those ideologies to spread. Then it either gets bad enough they take over (you know the site) or they break off wholesale and form a new community dedicated to those worst impulses (pyrrhic victory at best).
The best policy is to actively moderate, and in the case of the fediverse, defederate, those groups and those that give them shelter.
It solves a pretty hard problem that is a self-hosted video platform; a lot of places use YouTube to host videos, even if they aren’t doing so to make money through adsense, this is for their own site material, posting to groupchats, and similar purposes.
Issue is that otherwise you rely on platform owners like Google, who can decide to unperson you, your business, or an employee. It effectively happened to me, YT terminated my channel for unsubstantiated reasons, and hosting my own peertube is likely in the future to replace where I host my decades of video content.
Further, ideologically, we should be collectively moving away from “platforms” for what should be obvious reasons to those of us on the fediverse.