Each user can run their own software, either self hosted on a computer they own, or as a service. Kinda like a chat app, but with an open protocol. Then you ca

Each user can run their own software, either self hosted on a computer they own, or as a service. Kinda like a chat app, but with an open protocol. Then you can control who to follow and who can send you messages. And who can see your messages. Post group messages etc.