Ah, I see. It's a snazzy forum.
Yeah, not appropriate for anything that would be considered private or sensitive. In fact, most of the private lists wouldn't be able to use it because they could not comply with the Code of Conduct, since those private lists are *likely* to include discussions that include private or personal information.
Nonetheless, I don't have a baseline objection to those who are listadmins for public lists to consider supplementing (or, depending on their mailing list community) folding their mailing list into this. Perhaps it would draw more people away from Facebook and Twitter....although I suspect that people use those products for very different reasons that have little to do with Wikimedia work.
Risker/Anne