Why can't LP gains/losses be determined by performance instead of "MMR?"

I know you Plat+ players are gonna laugh your asses off at this, because you don't have to deal with those buffoons who go 0/7 in the early stage of the game because they don't know what their own turret is, but in silver, you have to put up with that bullshit every single game. I was really happy when I climbed out of that shit-hole and into Gold. I couldn't care less about Victorious Graves; I just wanted to know what it was like to get out of the literal slums of the League community and play with actual human beings who didn't program their keys into a bunch of separate bananas to play "with a challenge."

But the thing is. Nearly every single game I play, I start off going about 6/1/4 or something, and once the game ends, I get to 12/8/etc., because my team all went 0/5/2, and 1v1ing early is so much easier than 1v9ing in the late game.

Why does MMR have to punish the players who actually try to win games? Why can't those who actually attempt to do well have their punishments lessened, and instead dealt more harshly to those who feed? If this happened, the shit players would go back down to bronze MUCH more quickly, and the good players would have a much, much, MUCH better chance at getting to Gold.

I know the one main counter-point to this:

Why would you rather the game be unfair to the person who's "Just Having a Hard Game? xDDDD"

Well, if I did poorly in a match, I'd be less upset about losing LP. Because I'd deserve it. And every single feeding piece of shit in my ranked games would deserve it as well.

Also, put those "First Time Placement" people in Bronze, and not Silver. That shit's just wrong.