Blizzard's community has had it's really bad moments. There were several months during the "Burning Crusade" expansion where the forums and stuff in the game itself were very toxic. And that's putting it mildly. World of Warcraft was garnering a very bad reputation amongst gamers. A developer for another MMO once said during a press conference announcing their new game "We will not allow out community to become the cesspool that WoW is." That's some bad P.R. right there.
Today, WoW is a little tamer. But the community has really isolated itself despite Blizzard doing what it can to open up the servers. So, being social is often confined to your guild. It makes the game feel "dead" because no one really wants to talk. Trolls and immatures have driven everyone away. Now, even the trolls don't talk.
League is a bit more confined than WoW is. I think Riot has really done as much as they can what with the Tribunal and bringing in behavioral experts to help. I always heard that League's community was far worse than anything WoW could offer. The main difference is that when Blizzard bans you, your game software becomes useless because your game keys are often tied to your battlenet account. If you want to play again, you have to purchase a new copy of said game either digitally or physical copy. Many are not willing to pay money to troll again. League is free to play. If you are banned, even if you've never spent money on skins and such, you can just create a new account and start over.
