My analogy on why Feeders, AFKs, and Trolls are so infuriating.

Imagine the Troll, Feeder, AFKer is a Criminal he has stolen something that belongs to you in this case your LP, your promo game, or causes you to get demoted. Riot will be the police, that will investigate, catch and punish the criminals for their crime great job Riot.

The problem is that the damage has already been done, the property that was stolen from you (your LP, your promos, your rank) is gone. In the real world if the police recovered your property they return it to you. However in this case Riot makes the arrest, and prosecutes them for their crime but instead of returning your property they decide to keep it for themselves and give you the finger.

And that is why having a Feeder Troll and/or AFK screwing around in Ranked pisses so many people off, what makes it more infuriating is that it happens somewhat often, and why it feels so helpless, you are essentially being robbed of something you worked hard for and that it will never be returned to you, forcing you to earn it all over again.