@postmodern
The text-based open protocol has to be much more accessible than web-based chat options, unless we're using different meanings for "accessible". It also lets you use a web-based chat client or something like that for it if you want (and if there is one, I think there is), unlike some other services that won't even allow third-party clients.

My usual example for this flexibility in IRC is Microsoft Comic Chat (after disabling the noise it generates).