Why are there so many rage quitters?

THREE games now, I've lost due to people rage quitting after dying twice. There wasn't even any real reason. These were easy games, we were winning! I don't even want to try ranked anymore because that's all it is in low elo is people leaving the game. One of the games today our Ashe left just for kicks and giggles right before the first wave even hit. Our teammate who was feeding refused to early surrender. This kind of crap just kills the game for me.