The way reports work, and excusable AFK

I just recently left a game. I have been playing league of legends since I believe 2011, and I've left games before for numerous reasons. Never have I ever left a game because I became frustrated until today. During champion select I selected yasuo (more as a joke, but still it was selected) and someone on my team banned him. I asked why and then I was immediately flamed "what is your problem, it happens!" he exclaimed. I wasn't so much upset that he banned yasuo, I was more upset that there was no apology, and he tried to make it seem as if it was my fault. Coming into game Sivir, our adc, says into all chat "report lucian plz" (I was playing lucian top.) I really didn't see a reason for me to be reported, but immediately everyone hopped on bored the band wagon, not knowing any context. About 21 minutes in I was in the enemy jungle taking their blue in a way of counter jungling and a member of my team comes up and takes it, "mine." Seeing as I had been flamed for the entirety of the game I decided to base and just go farm side lanes until the game was over. Then Sivir says "leave" followed by kha'zix encouraging it. I was not going to just sit around a be criticized and trolled through a game that had already been thrown so I left. How many other people have been thrown into a hole of trolling and numerous people being pinned against you to no fault of your own. I find it very frustrating, and if the community in league of legends does not change soon I'm going to have to put it away, just as many people recently have been.