Competitive players being toxic.
I believe the reason some people do not believe they are being toxic is because they are competitive. If a toxic person sees his teammates as true equals and they mess up this would result in negativity. This is because anybody would want their teammates to care about the game and winning as much as they do. This is where the problem lies, for competitive toxic players, we expect too much. I think for those of us who do not openly flame and grief without reason, we can take a step back and look at what compromise we can have with riot. It would be to simply not expect as much.
The past few days i've been playing similar games and i've notice that if I think of my teammates as bad from the start I can not be mad at them, for they do not know better, regardless of Elo. I have literally gone every game without being toxic since because I just assume they are bad instead of competent people with a brain.
If you are chat banned right now and you do not see what you are doing is wrong, please take this as a warning before you make the mistakes I have made. Riot favors banning indiscriminately then to take it case by case.