It's tricky, though people are using them. Mastodon probably is seeing the most success at the moment. Over half a million users by current estimates. Not everyone who signs up stays around, but there's still quite a bit of retention. We could do better.
We need to make these things easier to host and deploy though. Having worked on MediaGoblin for many years now, I've found the most depressing part of it is that not only is it hard for people to start hosting things, it's even harder for them to keep it running... and it's not just MediaGoblin; you'll find this of most social network things. Most especially, people become afraid to upgrade their systems. I'm hopeful that systems like Guix will help in that regard, but that's a whole direction to explore itself: https://media.libreplanet.org/u/libreplanet/m/solving-the-de...
Yes. This seems to be a classic two-sided market problem. Developers won't flock to it unless there is a critical mass of users. Users won't flock to it until there are widely used and understood tools that are better than they have now.
We need to make these things easier to host and deploy though. Having worked on MediaGoblin for many years now, I've found the most depressing part of it is that not only is it hard for people to start hosting things, it's even harder for them to keep it running... and it's not just MediaGoblin; you'll find this of most social network things. Most especially, people become afraid to upgrade their systems. I'm hopeful that systems like Guix will help in that regard, but that's a whole direction to explore itself: https://media.libreplanet.org/u/libreplanet/m/solving-the-de...