If there is something out there that can do this, profitably, then we can kiss these mega social giants good bye.
I heard about the Blue Sky protocol, but it still feels primitive.
But socialising on the internet? There were plenty of options before, around and after then. Only, they didn't get the same support, convergence and effort since then. Because most people trusted the centralized services would opt to do the right things eventually. Ha. Fools were we.
Email is the real answer here, but the reason it is better is the same reason Facebook et al took over.
You don't need to use the internet to socialize.