I generally don't "chat" but rather am just here all of the time (open in a tab) and swing in to check new posts or work on a lesson.
I suppose the chat function would be great for an in depth discussion with a single member... on a topic or ten. Maybe a moderated interview even...
But chat? I have three messengers running and a cell phone as well as a land line right beside me. Why would I want to chat MORE?
Remember, wherever you go... there you are.