Punishment for people doing the right thing.. WHY!?

Just another salty post for a disgruntled bronze player in OCE, I just finished a promo game in OCE.. and the game starts as always.. and we get into position..and the lane phase begins.. nek minnit, bot lane racks up 3 deaths in 7min and bot lane tower is down in the 8 min mark of the game.. ADC afks.. and then the opposing bot lane rotates mid.. and Im out numbered 3 v 1 .. from there the game snowballs and the game is over with in the 18min mark of the game, as the mid lane outer turret is being destroyed. Just as it hits the @ 20 point the ADC logs back in, and continues the game as normal. I asked the ADC . "why did you afk?" the reply was, "i had to go and get some lunch".. At this point flaming starts from the other team members.. and the rest is history.. So, i just want to know .. why is it that I (and every other person that does the right thing in Lol) get punished, for the actions and attitudes of other players.. why, is it that I'm stung (and every other person that plays Lol) with a game loss, when some one else's actions are the direct cause of the team failing and a game loss? Why, hasn't Riot taken a leaf out of dotas book..and in instances like this ..don't record a game lose to players in the result of a player being AFK... Maybe something like this may just calm people down.. knowing they haven't lost the promo game. Food for thought?? or just an honest whinge?