If you haven't lost an inhibator and you have 1 or 2 fed champions on your team, and late game potential, why would you give up just because you are behind?
Its aggravating to see people throw away a match that is winnable. 10 more mins and you will find out. You already invested 20. Why give up?
It just shows that many players are just quitters, or have quit too much to be able to properly judge if a comeback is possible.
I think people who surrender too much should eventually get a ban. If you aren't here to try your best to win, in ranked, you shouldn't be queuing up. Its wastes everyone's time.