There are not really any clients for XMPP or Matrix that work as well as irssi or weechat for IRC. I also have more issues with servers for XMPP and Matrix (delayed messages, uptime, encryption weirdness). I use things besides IRC, but IRC still gets daily use and is my favorite. I suspect everyone who knows how to make a good client is still using IRC, so they aren't available to make good ones for the newer protocols.
weechat-matrix works pretty well, tbh. but agreed IRC is simpler to get right than XMPP & Matrix. Matrix stability at least is improving constantly though (but agreed it's not quite at the same level as IRC. Turns out decentralised E2EE is hard.)