Everything is wrong when people AFK during a Ranked game. Riot does nothing.

I'm fairly New to League of Legends, last month i decided to play Ranked for the first time, Right now i played 5 games ( still provisional ) and Lost two of those games because one of the players went AFK. at the end, that game still counts as a provisional game and now i know i will be ranked low.

Now the question is, WHY DOES IT STILL COUNT AS A PROVISIONAL GAME ? Seriously Riot does nothing to stop people from ruinning games.

PS : i know there will be someone who will say : " WeLl WhY DoNt YoU JuSt pLaY 4 v5? " my response : man you can't 4 v 5 in a ranked game, everybody there is playing to win, i'd like to see a 4 v 5 if we ahd the chance to get it to late game.