This wasn't my experience with IRC. Our channel only ever had thirty people tops before being swallowed by discord. It's got the same discovery/accessibility issues that the Windows vs Linux issue has. Want Windows/Discord? Google Windows/Discord, first result, done. Want Linux/IRC? Weeeell, first you're going to have to find a distro/client. There's no singular trusted expert and everyone disagrees on what's best, so you better pick one and pray it was the right choice. Oh, you'll also have to configure it a bit, or a lot if you chose the wrong one.
The thing is, my experience is different, but of course similarly anecdotal. I essentially got my entire professional network and career on IRC, and that includes contacts all over the modern tech stack and adjacent interests, being on just two IRC "servers". And I could connect many other people in the same way.
On Discord, there seem to be just more barriers against this. Getting someone into a new place doesn't just require hopping into a new channel with a single /join command, but an entire new "server" with a new crowd. There's more inhibition against that.
