In game AFK system

I usually dont participate in disscusions on forum so this maybe was a topic already so i apologise if that was a case. I am writing this because i was so revolted with my last ranked game. In my last game player left at fourth minute and we pretty start losing after that point we did our best but it was just unwinnable i lost my second promo game and LP. So system works like this if you was AFK you lose LP, if you came back and win you either lose LP or gain 0 i dont know for sure. So afk player is punished but rest of the team sufer penalty for no reason. Much better option would be if rest of defeated team dont lose any LP nor promos and that should occur only when system recognize someone as AFK dont you agree?