I have to post an actual POSITIVE experience I had with matchmaking yesterday to counterbalance all the negative.
At first I was paired with some terrible teammates (per usual) who were going 5-22, 3-16, etc. Then a bunch of people quit and my lobby got merged with another one. Played through the TDM match and it ended like 100 - 94. Pretty evenly matched. Everyone was somewhere between .8 and 2.5 KDr. And everyone stayed. Had 7 or 8 matches with the same group and all of them ended with a final score within 10. We even had a game that ended 100 - 99. Nobody really sucked, and nobody dominated. We even played Combine and everyone voted for the next map, not Combine again. It was like the heavens opened up and the perfect lobby was created. Eventually I had to stop so I could go to bed, but I wanted to message everyone from that lobby so we could play together again.
It can happen. Good lobbies DO exist.