To get the handful of people to collaborate and hopefully bring their friends. It's currently at 160 and climbing, no longer a handful, so it seems to be working.
What I mean is that I get the purpose of chat when the target audience is a small group of people that might have a reason to talk to each other.
The counter seems broken. It jumps from 100 to 250 then back down to 120. It did that a few times while I was reading.