As far as Microsoft's Install Bragging, I see it like a TV network promoting a show's ratings.
We'll take CBS' "Big Bang Theory" (the top TV comedy by far) as an example. You could put "Doggie Doo On Parade" after it, and a certain number of people would not change the channel. (I don't know what actually follows BBT on the CBS schedule, I'd have to look.)
CBS would put out a press release about X number of viewers who watched "Doggie Doo On Parade", not adding "but really, they were just too lazy to change the channel after Big Bang Theory".
I take Microsoft's numbers (or ANY such numbers) in the same light.
And no, I'm not comparing Windows 10 to doggie doo. I LIKE it, remember?
Press releases are not meant to be unvarnished truth. They're meant to put the company in question in a good light, and to put the information contained within in a good light.