#SSB ( #Secure_ScuttleButt ) seems interesting, but needing an invitation to a room server or pub server in order to communicate with anyone whom you don't share a local network with means that disconnected new users will abandon the network because they cannot view anyone else's posts and neither can other users view theirs.

It seems like this is an oversight, as I cannot imagine someone intentionally choosing to make a distributed network with this sort of dependency and few to no open-to-the-public general-purpose pub / room servers to join.