Yeah, nobody's ever written things that can respond to events by posting messages in an IRC channel. Shame, really.
The point is that Slack is much easier to configure. Writing IRC notification scripts tests the limits of the “10-year-old” level of difficulty.
I wrote my first IRC bot in Lua at 13, so you're right, it would test the limits of 10-year-old level of difficulty.
Regardless, it's not as if there aren't upwards of a dozen of off-the-shelf IRC bots you can grab off the 'net...
Actually I know several IRC channels that have bots that send messages for activity on GitHub, Twitter, etc. And writing IRC bots is among the easiest things ever. The IRC protocol isn't hard and there are lots of libraries, snippets and bots out there.