Have and afk or 2 and lose? Have LP lose like it's a full 10 player game!
Seriously though why is this a thing? Why do we have to suffer because some one rage quit or has crappy internet or their power goes out or any other reason for afking? We already have a system that tracks afk players so why is there no system that lessens the MMR and/or LP loss?
Personally, I think a system like this should have been implemented since the League system started, and honestly i don't think it is that abuse-able because at least one person get hit with a full LP loss for the game or even worse LP lose. Yes you can win with an afk player, but it becomes ridiculously harder with each afk player, and it happens more than people think, thought it is true that most games do not have an afk its still a terrible experience to lose those games and even worse when you lose MMR and LP for those games.
Also, for your information, of the last 20-30 games I had at lest 2-3 had an afk and we lost because of it or just made us even more less likely to have a comeback. Infact, I had a rare occurance my last ranked game of having 2 people afk in the middle of the game, which honestly 3v5 is basically unwinnable unless the enemy team is a bunch of dumb rocks.