Teamwork as a one-way street

Alongside the all assassin meta that has plagued the community for some time now, there is another meta that is substantially more toxic, especially in a game all about cooperation, and that is a supreme lack thereof. The idea that, no matter what role or champion you are, everyone is there to help you, but not the other way around. That if something, anything in your game goes wrong, that everyone else is to blame, not yourself, regardless of how massive or obvious those mistakes may be.

I keep getting matched in games with people who are extremely hyper aggressive to a fault, and before the five minute mark they've already died four times. They run ahead of the supports or whoever has the crowd control, burn every summoner spell and their ult to engage the enemy first, and usually they're dead by the time the rest of the team arrives. If they are last into the fight and both sides have already disengaged, they'll start up the fight again, no matter the odds, even if they are outmatched five to one.

If anything else, more than the assassin meta, the outright refusal to cooperate is the most toxic part of the League. The assassin meta ends up being the perfect conduit for this, because if you can do nothing but damage, there's very little room for teamwork to occur. Everyone is an island, in it only for themselves and see to such a short sighted degree all the wards in the universe would not help you.