I think it's more so the mods can keep up with the flow and also so that you "don't" carry on conversations.
I think they'd rather you exchange email addy's for that. That have pushed the "This is not a chat room" thing since I've been here.
That being said, when I check my messages and have 5 PM's from 5 different people, I have to stay on the computer for 20 minutes to respond!
SOMETIMES, just sometimes, I can't be on that long, lol