Whenever I think of MS Teams, I'm reminded of Paul Virilio's research on dromology ("speed as a weapon") and how the inhibition of speed (productivity in this case) can be a weapon too, whether intended as such or not.
They convince cost-sensitive IT infrastructure groups in other businesses to use Teams by offering it for free, reducing company productivity massively, hobbling product development.
Meanwhile, Microsoft adopt some other pay messaging/video service internally, accelerate product development 10x, become insanely competitive in a whole host of new markets rapidly.