For me the issue with the discord/signal/ telegram is they are all dependent on a 3rd party that could flip or disappear at any moment, to say nothing of the trust me bro privacy. On the other hand, email is an example of a communication system that would persist if the major supporters dropped out,but then self hosting email is a nightmare. Xmpp is better, but you still need DNS and TLS cents to participate. There are some interesting reimagined network options that seem like they could break this. My current favorite being RNS and LXMF