I generally disagree about the "pay to join" issue, but the thing you're right about is no viral/global messaging. That's the thing that really turns social networks into garbage. The problem being, though, that under late capitalism, that's what a large number of people really want out of them — to build a personal brand and social capital that can be converted into financial capital.
I understand the disagreement about pay to join. A social network needs to pay its bills somehow and there are 2 methods - users pay or advertisers pay. Or I suppose with sites like youtube its both (users buying stuff with affiliate links, etc.) Pay to join eliminates the need for viral/global messaging which is the draw to get advertisers. Influencers and the like is just bullshit and it promotes look-at-me behavior which is pretty anti-social. I’d argue those types of people are really noisy and fewer in number than casual social network users.
Maybe there is some middle ground where its free for users and advertisers can pay to advertise but there won’t be the viral content that advertisers want. One approach could be the local groups that naturally form - book clubs, mom’s groups, gamers, etc. could be tagged as such so an advertising model can happen.
In my opinion, users should pay for the upkeep of their social network; I just don't think that costs should be used as a tool to try to control behavior or filter out undesirable users (because I believe there will be many desirable users who will be unable to pay, and undesirable users who will be able). In general, I think the "Public Radio" or Patreon model works best for noncommercial social networks.
