afk problem

Like really rito...i win 5 games in a row...i get 91 lp and next game i get 2 guys in team that die 2 times and go afk...so we play 3 vs 5 and of course we lose...im not pro but i can win 5 vs 5 not 3 vs 5. The probl;em is that i lose 21 lp for that game...is it right? Whjy we dont have a loss prevention when we have 2 afk in team?