Actually, people have. They just haven't packaged it all up into a happy-clicky single click deployment. There is a little bit of configuration involved, but I have confidence that a majority of folks here could do it in two cups of coffee or less.

For me, it is Convos (web front end that uses redis for state tracking) + UnrealIRCD (IRC daemon) + Anope Services (channels, users, permissions, etc). It isn't as pretty as the Slack UI, but it could be.

Again, IRC != slack, they're not the same type of thing. IRC is a protocol, slack is a product built upon a (proprietary?) protocol that slack built to do pretty much the same thing IRC does (with arguably more features built in).

Also, no one is arguing whether people like slack more than IRC -- the point I'm trying to get across is that IRC is capable, but only lacks the development of a client, and forging of standards that would allow features that slack has.

All the bot stuff is copyable pretty much 1:1, the great design, and built in features of slack require a much better IRC client to be built. But that's the only thing standing in the way.

Taking the walled garden over developing an open source solution is widely accepted in the world at large, but it should not be the defacto solution for the FOSS community.