Not so sure myself. Seems like a whole lot of work to set it up, maintain it and monitor it.
I would think it would only work with a pretty high RA (just look at how much trouble the Mod's have keeping this forum under control!). In general to reach the higher RA's you have some idea of what you are doing, so how many 'urgent' questions would you really have?
Seems like a lot of work for little return. But hey, if someone wants to set it up...
I should mention that I have never used chatrooms, so maybe I just don't know what I'm missing.