It's what most users want.

Most users want to scroll through internet TV passively. However there is a big enough minority of users who want authenticity, novelty, and creativity in their online experiences. This group is big enough to sustain, say, a social network.

We've just never solved the Eternal September problem.

You're describing the cozy web. The Eternal September problem is actually solved right now it's just semi-invite-only.

I am a part of more genuine social networks now then when facebook launched. They're all around you, it's just "giant supermassive public square" never really worked even with strong recommendation algorithms to try to ad-hoc connect related people and cut down on the perceived size.

Most of them live on Discord, others on the fediverse, none are large by any metric and highly personal.