AFK/leave the game

Dear RIOT I have big question. Why when someone is AFKing or leaving the game and this is the main reason for lose of the game I have to lose points in ranked games? I lose and probably many others peoples tones of ranked points just because someone decided to leave the game. I understand that sometimes 4v5 is possible to win but most cases and up with lost. How about when someone is afking or leaving the game from instance he/she gets -100 ranking points and one "permanent strike" to be downgraded in league (strikes can reset after 30 days of no afk/leave) and rest of the people will have unaffected rating (also winning team will not get + rating points to make it fair or half of the normal gain). I believe that this is one of the reasons that there are good players in lower leagues and they can't go up because of afkers. I personally had 10 in a row loses and all of them were cuz of afkers. Once they leave the game it destroys morals. So at the end full team get easy win, team with afkers get slowly lose cuz sometimes they need to w8 before surrender. I believe that AFKers and Leavers should be more penalized for it. It is worst part of the game.