Yeah that's the issue with most self-hosted solutions. Pretty invariably they're either a pain to setup, require someone to provide an always on server (either in their house or pay someone else to host), or are hideous/missing major features. Discord does well because it requires pretty much zero setup on my part to have a place where me and my friends can chat while playing games!

Personally availability was always a major issue to me when it came to older self hosted solutions, with Discord I don't have to worry if group B has someone willing to bother hosting because it's always there hosted on Discord's servers and if something happened we don't suddenly lose our hub and chat.