Clustering and communities in multiplayer

So, playing SSX has been fun. It's nice to play with everyone, but the problem is that I don't actually have any friends who play sports games. Or racing games. Or hands-on-fire snowboarding games. So I friended some people on SSX  who picked up my geotags or whatever - but it felt kind of hollow. I've got numbers showing up on my global overview, which is nice, but I just don't care. There's nothing that actually links us.
Similarly, in Mass Effect 3, I play a game with people and then... never see them again. It's a problem in any game without persistent servers and communities and chats. I wonder if there might be a way to foster interpersonal interaction a little more.
The ME3 leaderboards will show you the performance of other people in your country, and in the world, and you can see the top of the rankings and you can see your vicinity in the rankings.
What if a game grouped you with a set of people, completely arbitrarily? Say that when you first log into the network, you get seeded with twenty other people, and it'll disproportionately choose those people when matchmaking. That way, you would consistently see the same people - you could get to know strangers by the way they play.
Better yet, it could be self-regulating, so that if you consistently lose with someone, they get filtered out - or do it by ranking and voting. The point is that it would essentially choose some set of people, arbitrarily at first, and give you those people as playmates.
Maybe it'd shift your 'location' in the space of players periodically - so you'd go a few weeks playing with some group of people, and get the chance to befriend them, and then you'd spend a while playing with other people.

I like Steam/browsable lobby multiplayer because I get consistent people to play with, and I like PSN/XBL multiplayer because I don't have to specifically find a group to play in. Why not get the best of both?