Yes! I'm an active IRC user for professional open source work (and personal projects) for the last 10-ish years. And still going strong.

What many people say IRC "lack" in comparison with Slack (or whatever new-fangled tool of the day is) are its strengths. What I value in IRC: lack of clutter, simplicity, bloat-freeness, open standard, and not least of all, blazing fast, among others.

Sure, IRC has its limitations, and is not suitable in certain scenarios. But is still shines brightly when it comes to distraction-free, text-based communication.

(I'm also hoping the Matrix protocol takes off.)

Obligatory XKCD reference:

https://xkcd.com/1782/ -- Team Chat