1v9 mentality

Everyone thinks they can solocarry, that they MUST solocarry, that everyone on their team is out to sabotage them specifically, and that helps contribute to the already acidic culture where no one wants to help anyone to the point that everyone goes all AD melee assassin, EVEN THE SUPPORT, expecting to win the game by themselves. They even refuse to leash for their jungler.

That culture needs to be dealt with. The game's imbalance comes from everyone trying to fill the exact same singular role and getting utterly crushed by not just a single champion, but a single skill, of which there are dozens, that counters the exact same singular tactic that everyone employs.