Not having a backlog is actually the thing I like about it. Discord (and Slack) have this thing where because there’s a backlog, people expect other people to have read everything. I prefer the experience where the assumption is that the people not in the room are assumed to have not seen a message. It makes it more unambiguously a synchronous experience, whereas Discord and Slack chat is pretty ambiguous as to whether it is synchronous or asynchronous.
IRC was bigger while I was growing up. But due to living with an internet connection that'd drop multiple times a day, I was never able to really use IRC because I'd ask a question and then get dropped. Getting dropped does not immediately log you out, the server has a timeout period. So when I'd get back in, I'd have to ask people to repeat whatever they said since the last timestamp I'd seen.
Not to mention some IRC channels are really high latency, you leave a message and someone else replies ten hours later. If you miss the reply because you were offline, you couldn't expect anyone to be around to repeat missed conversations back to you.
Due to this I've never really liked IRC, its not good for mobile devices or people who live with DSL or dial-up. Sure you can "just get an account on a bouncer" but that's pretty esoteric knowledge that I never encountered until after university.
