This is a more ranty post, again, feel free to tell me how I'm wrong
IRC is 'cool' and all (and I still use it for some stuff), but let's be honest here, it's not really a good alternative to modern chat services. It lacks so many features that are standard on even the most basic modern service. Yes you could implement things on top of it, but good luck getting every client on board with your 'IRC flavour'.
- No media support
- Unformatted only line text only
- No way to get messages when not online
- No audio/video
- No real way to save 'contacts'
I know Matrix exists, it also sucks (all clients are still basically beta, only one of them has the complete-ish specification and it still is very janky).