What you dont't realize is that your LP gains and losses ARE influenced bu your gameplay.
It is a common belief that if you play well, you win more often.
It is a fact that your mmr goes up when you win said games.
It is a fact that the higher your mmr, the more LP you get.
Therefore, there is an indirect correlation between playing well and gaining larger amounts of LP.
For example, if someone in diamond played 10 games on a silver account, they would play so effectively (compared to the average silver), that they would be netting a large win ratio. As a result of this, their mmr would go so high (raise even faster than his actual rank!) that he would be skipping divisions and getting 25 lp a game! crazy!
One observation i want to make about your post is that it seems the trend you want the mmr/lp system to be calculated in a very small sample size, say 1 or 2 games. the system in place is a system that works with how you perform on AVERAGE over LARGE POOLS of games. For instance, if you are better than your fellow silvers, then if you play 100 games of elague you are going to be gaining mmr/elo. That is not to say there wasn't a game where ur bot lane fed, becuase esometimes there is nothing you can do!
And who's to say that game you went 12/0 on yasuo is a telltale sign that your faker? if the system was based off small sample sizes like you suggest, then I'd be in the LCS already with some of these pop off games I get on occasion!
