Amen to that.
I am the opposite of a competitive person. I feel like a dick for winning, because I feel like I'm ruining someone's day. When I was younger, I would play Smash Bros. with my little brother, and he has aspergers syndrome. So back then, he would completely flip out if he lost, throw the controller across the room and storm off. Multiplayer was, therefore, the art of keeping him in his comfort zone.
I think because of this, for me, multiplayer has never been about winning - it's been about contributing to as enthralling an experience as possible for everyone involved. I never pull too far ahead in a multiplayer match - I always hold back just enough to keep things tense. So naturally, I don't find much satisfaction in Xbox Live - everyone else on there just wants to beat each other into the dust. If I play online, it's always for some form of co-op.
Plus I'm what I like to call a 'cinematic gamer'. I'm the kind of guy who wears shitty armor in Fallout because it looks cool, or tries to pull off stylish but completely ineffective tactics in Halo. So I suck at the sort of high-tension competitiveness that most multiplayer games demand. Gaming is about immersion for me, not the feeling of accomplishment that comes from victory.