Is demoting like this fair?

So this just happened to me today. 0 LPs, my toplaner decides to int the lane and quits the game after FOUR minutes. Do I deserve to get demoted for this? Ok maybe we cannot remake the game, but why doesn't the system recognize one of a team's member quit so early into the game to avoid his team getting heavily punished? Maybe the LPs lost could be lower and people at 0 LPs may be given some sort of "demoting protection". I think it's totally unfair for an afker's team to be punished for him going afk.