Disagree. As an open chat platform -- ie. not for private/confidential communications, to me, IRC is still superior to Matrix. We use it at work in parallel to IRC, and it still happens today (at least with elements.io) that a message or two can get lost when you restart your client in an unfortunate moment, and sometimes channel user lists get out of sync, so you're addressing a person that's not there, or suddenly someone replies you don't see in the user list. It's happening rarely, but it does, and it is annoying.

IRC's concept of requiring an active TCP connection for your session is archaic but dead simple, and the only times you have to wonder whether or not someone received your message is if they got a ping timeout shortly after, and the user list might get out of sync once in a honeymoon when there's a net-split. Nothing about IRC changes anymore, so you won't get surprised by regressions and bug fixes every month. I can see how people miss long multi-line messages and animated gifs in IRC, but I just don't. It's straight forward text communications, no bullshit.