People refusing to report
I think it is very true that a lot of the problem with bad behavior is that no one will report on it. One of the best examples I can give is when people AFK. I can't tell you how many times I have a teammate AFK and the enemy team refuses to report them. I suppose they figure that the person being gone gave them an advantage, so... Easy win for them?? I've also had people refuse to report intentional feeders. Why? Because that feeder allowed them an easier chance to win.
Sportsmanship is nonexistent since people care so much about winning, they don't want a game to be fun or challenging. I for one hate it when an opponent feeds or quits. It makes the game really easy and unenjoyable. If I wanted senselessly easy, I would stick with AI.
I can understand someone not reporting someone for verbal abuse if they never actually read what the person said. But, everyone present during the game, can tell if someone is missing or feeding...