My least favorite toxic behavior (Long)

I personally don't troll and am absolutely never toxic; not that I'm better than anyone else, I get just as frustrated and angry when I do bad or when I get a team that seems to make the same mistakes over and over, I just don't express it because it doesn't help me feel better and it never helps the game go smoother. So on the other hand, when players say horrible shit in chat, I either (rarely) try to mitigate and make them feel better by trying to say something passive and hopeful, or I just mute the entire team so I don't have to be exposed to the negativity. AFKs and griefing by feeding kills is even more annoying, it brings a hopelessness that robs me of my desire to play, but I do my best to try and use potential honors and the offender getting reported to make me feel better (not out of spite, I just hope the system eventually works to help weed out the toxicity).

However, there is one player behavior that infuriates me so intensely that sometimes I have to idle and try to calm myself down, and that's when allies intentionally move to steal farm or buffs out of spite, even more so when they don't need it. If they can obviously use the buff/farm and they ping, I generally don't even question it and give it to them. I am so against toxicity that I will hurt my own farm by handing over what is being asked for in order to prevent potential saltiness.

But when you obviously don't need, like a Vel'Koz support in one of my games that took our jungler's red buff 3 times (twice burst stealing it from under him), "Because he deserved it" (in my opinion, the jungler did nothing wrong), it's such a shitty, negative thing to do that I wasn't even upset when the jungler decided to afk. In another one of my games, our jungler was so upset that I said "You're behind, don't worry about ganking top, just farm up." (and that is verbatim, and it was the only thing I said for the entire game) that twice he waited for me to go to a minion wave, chased me, and burned his flash over a wall just to burst down the wave, without pinging his intention to clear it. He burned his valuable, high-cooldown summoner spell TWICE just to prevent me from farming, out of spite, even though I would have GLADLY given it to him had I known where he was going. This has happened to my team four times tonight and it is such a shitty thing to do that I considered quitting League for as long as it took for me to forget how terrible the game makes me feel (last time was almost 8 months between the end of season 2 and beginning of season 3). Which, I get it, not only is this the internet but since I am telling the most toxic gaming community since Halo that I considered quitting, I am subjecting myself to hateful-for-fun taunting to go through with it because as a Bronze I am not a valuable anyway, but that's not the point. The player of a competition, even in an unranked normal, shouldn't have to feel like quitting because of misbehavior that is practically legal and allowed to go on.

Any competition between skills is a sport, I've accepted this. So, if any of you enjoy physical sports like baseball, football, or whatever, how irritating would it be to you as a fan when your favorite player decides to retire because their teammates are allowed to get away with hindering the player out of spite? Maybe that's a bad example, but I really don't know how else to express my frustration at this kind of thing, especially because it isn't "against the rules" and can't really be enforced.

My QQ is over, proceed to spam TL;DR