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for the average end user: heck no.

for those with budgets to hire server administrators (or pay for third-party managed services)? yes.

second category includes almost anyone with a large following like institutional users.

hell the incumbent social media service operators can white-label their existing software and sell this as a service.

Not really many open source project such as nextcloud, mattermost are easy to host your self, or the hosting provider provide it as an app.

Yes. Like some sort of workspace? Google could make one. I wonder what they'd call it?

I’m sure Google wonders the same thing, given that it’s had like five different names over the years.