Not just a culture clash -- classes of contributors

I've spent a bit over 4 years working on Gentoo, a project with a major IRC component. I'm
logged into IRC 24 hours a day via screen session running on a server, but I only check in for
messages, similar to email. When I have a message, I can check whether the sender's present
and immediately have a realtime conversation and get things done quickly. As someone already
mentioned, just because you're logged into IRC doesn't mean you're staring at its window all
day. The same is true for both email and IRC -- you can waste hours on it, or you can be
efficient.

Another thing I've seen on IRC is growth of a tighter community, where people actually get to
know other people instead of merely have technical discussions with them. I've also seen that
far fewer flamewars happen on IRC.