I think your observations are accurate. I've also noticed the problem, and that private-ish group conversations like WhatsApp groups and small Discord servers are so much better than Facebook, Twitter, Instagram and co. The only problem is discoverability -- because groups like these are private, it's very hard to discover the ones you'd like to join.

I'm currently working on an early-stage startup on this space, and we're specifically trying to solve the discoverability problem while keeping the group chats themselves small and private (or at least private enough). Do you think you could see yourself using something like this?