They're still out there and mIRC is still being sold to access them. In fact, instead of big networks of channels, there are now an amazing array of small networks, some of them, like Bartcop, niche networks with only the one channel (or he used to run his own server for it, dunno about now).
The best channels are moderated and moderators are able to toss out anyone who gets really rude.
It's the place to go for international real time chat as it's a way to talk to people all over the planet and it's just difficult enough to use that it weeds out a lot of the riffraff you get on other chat formats.
In other words, conservatives on IRC can mostly spell.