Why is this game riddled with toxic little babies?

I've played a bunch of NORMAL games. Some on a different account. In each one, I've had to deal with teammates that were more toxic than anyone I've ever met in Bronze or Silver elo in ranked. I had someone pick Brand to go bot lane instead of an ADC, saying "he does it all the time, it'll be fine" > so I gank his lane and get a kill > he decides that it was a "kill steal" and literally ragequits because of it. This was in a premade where I was the solo Q'er. This guy was also saying after my FIRST death of the game that I was "feeding". THEN the rest of the team decides to flame me in /all chat when I did nothing wrong. This is absolutely unacceptable behavior and I don't understand where it comes from.

In another game, my bot lane died 25 times in 29 minutes and we had to FF. In that game the team raged at each other instead and I hardly said a word. Got reported anyway.

On my other account I played ADC bot, with a Cassiopeia support (this was at gold-plat MMR) that whined and raged the entire game, took a whole bunch of CS in lane (which doesn't really matter to me, just was annoying) while going 0/5 before I died a single time. I started roaming around because I didn't feel like laning with a total jerk.

This game just isn't fun anymore. I'll be playing Hearthstone from now on where there is no chat to be toxic in. You guys think Riot is ruining the game, I disagree - At least Riot knows how to have a civil discussion with its players, and is open to feedback. The kids in my games don't even know what the word "civil" means, and if you try to explain it to them, report you for verbal abuse