I got banned from League of Legends, by being negative? What?

So I was in a normal game, I was just trying to have fun, but I got camped and was preety much useless for the rest of my game since I was playing . I was trying to recover, by trying to stealing a couple of kills or farming very hard, but my fellow adc player, who was also a very kind person, kappa, decided to take all my cs when I wanted to cs, and when I finally got to farm, I got flamed for not grouping with my teammates. Ohh and btw. I had 11 assists as an assassin midlaner by the end of the game. No wonder I was useless. I didn't flame anybody in my game, I was only trying to defend myself from the flaming. The only 2 bad words I used were: ''retard'' and ''degenerate'', and I got perma-banned for that it looks like. I really don't understand the banning system in this game... It punishes people for ''talking shit'' but it doesn't punish the intentional feeders, the trolls, the afk's, and the players who find pleasure in provoking other players and pissing them off with their mastery lvl 7 spamming. I bet that the guys who were flaming me for the whole game didn't get anything...