Riot enforce the blocking of players

It's bad enough, you cannot get a 2 a three game winning streak without a troll or two in my case always ruining it. But why are we forced to play with trolls we blocked already. They are two numerous in number to count. I can't remember all of them. So, they end ruining any chance I have of moving up because they flood the lower elo or levels or whatever you want to call this crap. It's BS and ruins the game to have this kind of crap going on. How many people have quit the game because of this crap!?!?!?!? But the higher elo players don't give a damn because they are removed from the situation! This game is becoming a joke, it will continue to be one if low elo players keep running into road blocks at every turn.