There was a post somewhere where someone asked if the Arab Spring or Black Lives Matter could have gotten started on a platform other than Twitter (and, ok, i guess fb too), and I think that deserves careful analysis.
On a smaller scale, people have used twitter to ask for help with local problems (e.g. "my spouse is missing, please signal-boost").
There's a lot of social good that was made possible by the "Follow" button; by the ease in posting photos & video to all followers (e.g. video of abusive & violently criminal behavior by the police); by the fact that an account wasn't tightly bound to any one community or topic (and by the fact that we didn't need to make one account for local-neighborhood issues, another account for cat photos, another account for following political topics, another account for pixel art, etc); by the fact that involvement didn't require learning about HTML or CSS or SSL certificates...
And even if someone takes care of all the technical stuff for you by running a local server, what prevents them from being irresponsible with that platform? Distributing power doesn't mean there won't be abuses of power; it just means you're less likely to hear about abuses on the servers where you personally don't have an account, and that there will be a larger demand for more people to run operations because now there are many more self-contained sites that need attention. That, and/or many users will simply give up and not connect, because who has time for that besides righteous computer nerds? (And, as a computer nerd, I don't want this for us, because we already have plenty of other problems that we're trying to solve and not enough time to solve them.)