This is what boggles my mind. We're talking decades of arguments and discussions, dozens of different ways to do it, with dozens of tradeoffs that you could start listing with 20 seconds of thought, and still people just pop in like "why isn't it simple??" as if that's some award winning insight.

Come on, try! Start listing some of the core features of the different protocols/clients and answer your own question as to why it isn't simple! Presence. Chat history while offline. Threading. Mobile devices. Intermittent/mobile/cellular/wifi/CGNAT connectivity. Multiple clients on the same identity and presence. Identity establishing and confirming. Encryption. End-to-end encryption. Backing up and restoring chats, encrypted chats, group chats. Federation. Friends/groups/permissions/trust boundaries. Markup, markdown, formatting, images, emoji, unicode, code blocks. Audio, video, broadcast, multicast. Discovery. Extensibility. Federation. Store-and-forward.

> "We've been sending text over the Internet from the moment the Internet went online"

And IRC has RFC 1459, RFC 2810, RFC 2811, RFC 2812, RFC 2813, RFC 7194 and it does almost none of those things.

And you can still use IRC. But IRC is not good. At this point it's either wilfull ignorance of what people use computers for, or it's indistinguishable from deliberate trolling.