Because I don't stop being the last in the games. People have a very fast reaction time compared to mine, people know how to shoot, I don't. I have played enough hours already and I think the system should match me against bad people like me.
I feel that for quick games there is very basic or no matchmaking at all. I've noticed extreme stomps and one or two players who are way better then the rest of the lobby. This might be due to the lower playerbase of the beta, making it harder to create even games. I can't speak for the ranked system as I haven't played ranked yet.
It's possible that being a beta there are few players (although I don't think so, it finds a game instantly) and that is why matchmaking does not work.
Maybe when I play rakeds the games get better...