$oldjob had that too, and it worked really well for most people - tech and business alike. I like IRC because it makes you focus on what really matters instead of some sort of seamless Giphy or Wikipedia "rich"-content integration. It's sufficiently async to not bother me at all times, and I can interact with it programmatically very, very easily.
Also, due to its rigidly ephemeral nature (ultimately depending on your personal preference of course, but the default for most clients these days - and opposed to something like Teams, which seems to store everything forever), it nudges its users to use a more suitable, more permanent medium to capture information that is to be persisted. It's clearly a different kind of animal than a wiki or an email archive/mailing list, whereas new "alternatives to email"-tools like Slack, Teams and their ilk are anything and everything in-between, which causes "now where the hell did I read that thing about that other thing..."-syndrome for me.
Also, due to its rigidly ephemeral nature (ultimately depending on your personal preference of course, but the default for most clients these days - and opposed to something like Teams, which seems to store everything forever), it nudges its users to use a more suitable, more permanent medium to capture information that is to be persisted. It's clearly a different kind of animal than a wiki or an email archive/mailing list, whereas new "alternatives to email"-tools like Slack, Teams and their ilk are anything and everything in-between, which causes "now where the hell did I read that thing about that other thing..."-syndrome for me.