What? New people will always be playing this game. There's no "crowd" that causing this problem, it's the way the system is designed. New faces and places aren't going to fix it. And people are certainly going to quit still, very much moreso than past Halo games.
Two playlists isn't really a good variety as a substitute. Seriously. Telling me to play arena(which ranks reset) so I don't encounter quitters should show you how borked it is.
But why should allllll those other playlists be thought of as social? Isn't that a bad thing? The social matchmaking was fine in Halo 3 because well, you knew you were consciously playing social, and quitters weren't a big deal. In Reach, you have no choice at all but to play with them.
... Except it's magnitudes worse than Halo 2 or 3.
I feel like you're being apologetic for Bungie and I'm not sure why. What they have set up now is head-scratchingly strange and the more people try to explain it, the more it seems nonsensical. I like the game like I said and I'm trying for the ONI run right now, but looking at it from an objective viewpoint, it's hard not to point this serious flaw out.