I don't think that's the strategy at all... the point is that most of the negative rep Vista gets comes not from how the OS actually is, but from the highly publicised (and often misinformed) bashing by Apple and the like that people buy into so easily. Hence the rating for "Mojave" is twice the rating these same users gave Vista, the same OS. I suppose another way to interpret it is that people who say Vista is terrible generally haven't actually used Vista.