Loss Prevented with AFKs

Have you ever played a ranked game where you have 4 friendly guys on your team having a fun time then your fifth decides to rage and afk?.. I know I have.... and the crap part about this is that even though it is an unfair game, you still lose your LP. I believe that in this scenario, the winning team should still get their earned LP, but the losing team that had 20%+ less players than the opposing team should not have to lose LP over a game that there was little no chance in winning. Rather than taking LP away from them, you should simply make the game loss prevented for the team with afk.