That is why I literally said in my second paragraph that "hosting [...] your own server would probably be the best choice". Also, I was replying to somebody who complained about connection issues on his phone. He probably doesn't want to have a random timeouts when he travels from one place to another and potentionally miss important messages...
Furthermore, IRCCloud is not centralized in the same way as Discord is because you are not forced to use it. IRC is still an open protocol. For example Matrix has a big chunk of people using the official "centralized" Matrix server and the same is true for Mastodon with mastodon.social. Some prefer to self-host, others do not. I don't see the problem here. Gmail wasn't the downfall of email either.