[foobarbazqux]

I had honestly never considered the idea that it could be seen as condescending to express anger while taking pains not to humiliate the other person. At least I think that's what you're saying. Maybe there's another way to say it without the abuse?

In a boss-employee relationship, the boss is not your friend, so they are an authority figure, much like a parent is an authority figure to a child. So it could be in the nature of the relationship. I wouldn't talk to a friend or coworker like that, I do see how that would be condescending.