Actually, if anything it's Sony that detracts from the mix, because you absolutely need to buy a PS3 to play them, you have no other option.
With a lot of MS exclusives, you can either get a PC version, or wait, like, 1 year to get it on PS3. Gamers have other options other than 360.
I have both a 360 and PS3, so it really doesn't affect me, but saying Sony is adding and MS subtracting it is a load of bs. And I see the only platform you don't have listed below your avatar is a 360, so I guess I know where that comment came from.