How is trolling games a tolerable offense?

Get a support in ranked, troll enough but whatever I can live with it and carry it. Then in champ select he decides, "I'm going to jungle" and takes instead of . Whatever, I'll carry him. Then we get in game, he refuses to leash me and runs to bot lane enemy bush. I ignore it, and come to the bush about 1:30 in. FIRST BLOOD. Heimer says "Lol guess enemy jungler started blue, didnt see Sona and Jhin on top of me lol". Then he goes afk under bot tower for a good 3 minutes when he tells Jinx "lol youre bad have fun with this game" and afk's for 10 minutes. We're still chilling, Darius gets some kills and its Darius so we can still win this. Then dingler comes back in, and starts following me around my jungle smiting my mobs away from me every chance he can get and leaching xp. I say fuck it "If you want to jungle, I'll support. Just try to win". Then he decides "Darius is too far ahead, lets go feed top lane". Goes and gives nasus a kill and nidalee a kill then afks in base some more. 30 minutes in we decide enemy team is too far ahead now to 1v4 and we attempt to ff, dingler then decides to all chat verbally abuse our whole team while refusing to ff calling us all noobs and ruining my promos. On top of all this dingler KS'd every opportunity he would get so he had a positive kda so we cant report for intent feed. Please tell me that not playing your role dynamic que gave you (without the approval of your team with a role trade) is permanently bannable please. Dont need more kids like this ruining the game and my ranked experience because shit like this is happening wayyyyyyy too often.

on a side note WTF is up with the lp loss on losing promos and getting demoted. My average lp loss is 15, but when i lose my series I am put at 54lp (23lp lost per lose) and when i got demoted first loss at 0lp, it puts me at 64 lp (36lp lost per lose). WTF??