Fact is we all see the threads and hear all the complaining from people in lower elo that either matchmaking is rigged, or their feeders are just too much, i want to point out something for these people however that might actually change what they think.
First off, some games you can't win, this is a simple fact, however this is only about 15% of games (and that's being generous.)
Next in your win rates you can win roughly 40% of your games by not feeding and just being useful in teamfights, and by this i mean you can go 0/0/0 in lane and keep your laner from roaming, and you just won around about 40% of your games
Then you have another 15% of your games, where you don't have to be ahead in lane but if you make good plays and do your job, you will win these games (so you can win about 55% of your games by not fucking up).
the last 30% of your games, are games you have to hard carry, if your not 10 kills up and roaming and winning the game for your team, you ain't going to win these ones.
Now what does this mean for you, well here's a few things.
1) if you don't have a 40% win rate, your feeding and losing the game for your team, your team would carry you if you didn't feed.
2) if your sitting on a 50% win rate your actually not as good mechanically as you think you are, and are right where you belong no matter what you think.
And here's another bit of food for thought, a majority of challenger players win between 55%-70% of their games, and they play against diamond+ and boosters can quite easily get win rates of 80-85%, so what excuse do you really have for not winning your games?
Quit trying to blame your team, they will screw up as much as you will, because your probably where you belong.