dota 2 does not have a tribunal. there are less toxic players there and they all play to win. i have never seen anyone intentionally feed. they do have the occasional flame but that is to be expected in any game. even when they do flame it is a lot less worse than in league and does not last all game. there are also less leavers and afkers, but that might be because they dont count the game if someone d/cs too early in the game.
but not only comparing it to dota 2 even all of the other mmo games out there league is probably the most toxic. it is strange because they even have a policing system, the tribunal, set in place. it is also possible there are more flamers/trolls because of the snowball setup of the game.