Possible LP improvement idea

instead of losing 20+ LP a game when we lose, why can't we lose LP based on our grade that we are given? Let's say you go 20/3/5 and you still lose because your team fed as well as kept on making poor decisions. You did the best you could but you still lost. I think it is unfair to lose 20+ LP even though you did well. I'm not saying just because you did well, you should still gain LP if you lose. My point is that the amount of LP lost can be based on your grade. For example, if you got a S, you would only lose 5 LP, A = -8 LP, B = -11 LP, so on and so forth. I just feel that this would be a more fair LP system. I know league is a team game but sometimes you can't control what the other players on your team does during the match. I hope i was clear in making my point. Feel free to comment your opinions and/or ideas.