[Warning: big post ahead, just felt like adding some relevant experiences of mine to the discussion]
More to the point, a fair portion of the people on IRC also happen to hang out on Discord too. So essentially it's the same people as on IRC plus some extras! Almost makes you wonder what the difference between Discord and IRC is (no don't answer that).
That said though, I'd also say (to a point) many of the old IRC residents themselves have grown up over the years. When I started going to #srb2fun and the MB myself nearly a decade ago, I didn't exactly get the best start as a newbie. I think I was considered a bit slow or under a rock etc, and perhaps a bit silly. So as you can imagine, at times I wanted to stay away - I remember hanging out in sub-communities such as SRB2 Wadbase (unrelated to Skybase) to do so somewhat.
But as I stayed on, some of the worst people were outed or left anyway, and others became more reasonable over time. And surprisingly, some of the younger ones even turned out to be reasonable people who make really cool stuff! I'd say now the people at the IRC channel, as well as the MB, are much better than they used to be.
I've personally tried to be reasonable and helpful to new people so they aren't put off like I almost was (at various points), but it's not always easy. If I have personally put people off our community, please forgive me. I'm not scary, honest! =(