I Don't understand why after having an 'INT Feeder' lose you a game also leads to a loss of LP

I just played a game and we were doing very well until our mid-laner {{champion:157}} who decided to int feed after being ganked twice and lost us the game because the enemy jungler and Mid-laner snowballed. (He apparently had 10 accounts banned) I was 1 game from my promos, and I lost that opportunity all because of a troll we shouldn't have to lose our chances of getting a better rank because of an inting teammate I think there should be a system where if there is a troll/griefer in our game and we decide to report him and he gets a punishment we shouldn't lose something out of it. It's like trying your best to win a race but the floor is made of ice and rocks are being thrown at you from the crowd. please up-vote if you agree.
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