Complaining grounds? Are there any?

OK it's really quite simple. I am just curious. There used (and still is) a thing such as kill stealing or "kill securing". But at the end of the game what matters? Objectives? Kills? Gold totals? What about damage? So it's still going to happen. You will lose a game and then someone will always try to blame you. How can they talk when they have the second least amount of damage on the team except for the support and they are the Jungler? To top it off you have the highest amount of damage on the team. Does it matter?