I am saying that his wins mean less without facing his rival. It's like taking a multiple choice English test without the written essay part that you suck at. Sure you got an "A" but someone omitted the biggest part of the test for you.
The point is to win tournaments, not to "beat that specific guy". Pete Sampras would only have five majors if we only count the ones with Agassi and the rest meaningless by your logic. Nadal would also only have six (vs rival Federer)