This might be (just a little) too pessimistic.

The sweet spot both Tent and Diaspora are/were aiming for is one where most users use somebody else's service, but a few crazy neckbeards choose to self-host.

The neckbeards who actually care (often quite unreasonably) about privacy, etc, provide a very useful service to the ordinary users - they keep the central service(s) honest, ie, keep them from turning into Facebook. Because it's possible to escape, because the neckbeards keep that possibility open, the ordinary users are not captured.

At least, that's the theory. Diaspora didn't execute on it. Tent, well, we'll see.