>It's not clearly labeled, it is a very small label with white text on a pale blue background in an already very busy UI.

You piled a whole lot of arguments, but doesn't change the fact that it's still clearly labelled. Besides, you only need to notice this box once to be able to tell whether something marked the same way is an ad or not in the future.

You're absolutely right on the real problem: it's allowed to present itself, totally convincingly to the average / naive user, as Microsoft sanctioned.

> the fact

Your opinion.