Unfair game

Did anyone get the same problem as me? So here the thing, in a game, my team and I tried so hard we got really good kda, but at the end, we lose cause one of teammate throwing game or sometime afk. It is not fair for us the players who try hard and want to rank up their rank but got demoted or reduce point because of player who want to troll, or afk, or throwing a game. Why people who trying hard got nothing and get the same reduce point with troller or afk or throwing game or toxic player. I hope riot could do something about that for the next season. It not fair for people who try hard.