Why do afk'd games STILL count in ranked?

This is a legitimate question, not a rage thread. I've been tossing this around in my head for a while, as all my friends complain about their leavers.

Why do ranked games still count if you have an AFK on your team? I recognize that it doesn't happen nearly as much as people think (you always remember the bad more than the good). But to be stomping a game so hard, then lose it because someone vital left? Or lose it right from the beginning because someone left? That's not a reflection of player skill or anything. It's an unfair disadvantage, and you'd think a highly competitive game would try to prioritize at least BASIC fairness.

I can't actually come up with an answer. I don't believe that "people would abuse it to get loss prevented" is a valid excuse, either, because of the nature of what some kind of AFK protection would be; the game doesn't count at all. For anyone. Except the AFK. I don't care how good of bros you are, no one is gonna keep dipping for the sake of his or her buddy's LP. Riot, please, be progressive for ONCE; AFK protection in ranked. Reduce the frustration, reduces toxicity, people play the game more, people spend more, everyone wins. It's a step in the right direction.

Sincerely,