This will receive many downvotes but I dont care.
I've heard that phrase many times. "Everytime I lose, I didnt carry hard enough." However the reality is not every game is your fault. Yes, there is always something you could have done to help your situation, but think of it this way. You have limited resources such as time, CDs, dmg, gold, ect. Theoretically, there is a perfect way to use those resources, BUT even if you do use those perfectly, that game may still be unwinnable. You can produce the best outcome possible, but it still ended in a loss.
My point is not to complain "I was 1,835,235/2/123 but we still lost cuz of my stupid team". My point is, your perfect use of your resources can be outdone by the other team. Since no one is perfect and can produce that outcome, you can always learn from your mistakes.
TL;DR You could always play better, but that doesnt mean you could have carried that game.