> A server like Marvel Rivals has literally millions of users. Players join that discord to socialize with all of those players and build a community around the game.

Going back to something you said earlier:

> Rocket chat is a Slack alternative for people wanting to host a server for a community. It's not a platform, you need to register and login to each server manually.

So the primary thing is that there is no SSO for each server? No centralized auth system? Because everyone I know that uses discord 'found' the discord via some official means of those million person discord's like the official Marvel Rivals one. If the only purpose of the centralized system is not requiring a new login for every server, then a centralized auth system could be implemented by relying on people's other social media accounts. Login with Google/Facebook/Apple etc.