Stop blaming others. Nothing will change unless you start asking the right questions. It doesn't matter that that other guy on your team went 0/10/0 at 15 minutes. You can't chage that. Will his feeding lose you the game? Maybe. But at that time, you need to not waste time with the whole "noob, report" or "X fed so hard, gg". Instead, you need to ask yourself, what you can do. And if you still lose, don't waste time thinking about that other guy. Ask what you could have done better that game, and use that knowledge in the games you will play after that.
Your team can stop you from winning a game. Even a whole bunch of games if you want. But what they cannot stop you is to climb. Because as dumb as your teammates are, the other team is no better. Even if they get fed, they are still dumb, and you can use that if you know how. As long as you are good, you will always win more than you lose. And if you can't notice the signs that show you how to make a comeback, and how to use your opponents' weaknesses, then that is where you need to improve.