So we used to have this thing called telnet BBSes in the mid nineties.

Discord is not too similar, but typically with less moderation. Bunch of people talk about stuff in subject based rooms, there’s some administrators looking after the health of the channel. Join or leave rooms, etc. Open source would shield it a bit more from commercial interests.

Social media is simply too big for this, it will always be advertised run because of the size of the audience. Also the viral component and manipulation affect how valuable it can be.

Build and join smaller communities.