Use cases for chat rooms

I'm working with a startup with a prototype of private chatrooms/voice/etc.

While this clearly solves some of my company's needs, first, I realize those are somewhat specific for my businesses, and second, I'm wondering how common is the problem statement?

What other businesses might need private communication channels, as 1-1 chat rooms, etc, and that they have not been solved holistically yet?

Doctors? Sales? Support?

I'd appreciate few specific examples if you don't mind sharing.