I actively avoided IRC for years. I still avoid it whenever possible. And I've been developing and sysadmining for the web for more than 10 years now.

Frankly, it boils down to that I just don't like it. I'm more interested in getting better at programming, or learning about containers, or some other useful thing, than trying to figure out IRC's odd interface. Chat isn't something I should have to think about. It should just work.

So, I agree with most of what @vonklaus said, and disagree with the links pro-irc stance.

I've never used Slack, so I have no opinion on it.