What, no helpdesk synonym starts with 'b'? Seriously, though, this thing seems very powerful for businesses not tied down by regulatory constraints. I like the idea of 'rooms' and a centralized single chat interface.
While I've tried to keep scaling in mind so huge businesses could use it, I think the real sweet spot for it is smaller distributed workgroups. I'd be less interested in seeing a 20,000 employee company adopt it than 500 companies with 50 employees, each.
And I really want to reinvent voice/video "calling". I think "calling" is a weird, old paradigm and rarely needs to be done through its own standalone app. If we're collaborating on the same thing, we should just be able to talk. If we're in the same #channel, we should just be able to talk. I shouldn't need to get in Zoom or Discord or something to chat while we draw on a whiteboard.