Why is everyone so angry in this game?

This has been going on for some games now. Each and every game that I play, I have to deal with such angry and cruel people. Constantly flaming each other and ready to beat each other up when given the chance. I am a lvl 13 player, so I have to deal with this a lot. I have to play against players who are at higher ranks and are smurfing or players who are running a bot program for the level grind. I was getting flamed a lot by a duo bot and I was the one who got chat restricted. Yes, I do agree that I should not have lost my temper but sometimes there is only so much I can handle. I had to leave a game because the ADC was constantly flaming me for stealing his kills when as a matter of fact I had to clean up the kills since he was the first one to die whenever I ganked his lane.

Take a look at this images. They are from the same champion select. https://imgur.com/a/mCbGT

For context, ADC banned Swain whom support had selected to play. And just for asking why, the ADC went on a tirade.

And this just the tip of the iceberg. Even new players refuse to listen to those who have been playing the game for some time,, no matter how nicely the smurfs are, so the new players aren't just the victim. The funny thing is if this is the condition in normals, i really don't know what will be the case in ranked