The toxic part of the community

Pretty much. They dont take any blame for their actions and insist "someone made me do it".

There are like babies who complain to their parents that the parent made them have a poopy diaper.

More than half of em don't even realize that what they are is just a Grade A asshole.

"No, it's not me being an asshole! It's you being too sensitive over the internet." It's the internet? Yes, it is, and feelings get hurt over the internet. Feelings matter, sorry bud... Now, why do you feel the need to be an asshole to others over the internet?

And can you guess why they usually feel the urge to be a jerk to others over the internet? Insecurity.

{quoted}

I feel like it sums up part of it

This is simple to understand. You can't force random people to work together and care about each other if there is no incentives to do so.

Who ever gets the kill gets the gold. That incentives players to fight with each other for the kill.

Front line champs/ supports can't take long amounts of damage anymore like they use to so there is no incentive to play tanks, or front champs anymore.

The game promotes players to be cocky if they do well.

Being nice would help, but there is no incentives to do it in this game.