From my Dota experience, usually the hostility is between teammates. Because League partners 5 people together, mistakes and bad play from your teammates can have negative impact on your hero and this can be quite frustrating. Over-extensions from a team mate can lead to your hero also dying as you try to save your buddy. It is also easy to blame your teammates when you make a mistake.

No, hostility in the context of playing the game is fine. Its a PvP game so that wouldn't be a tenable policy. You can go and kill the other team all you want. Poor behavior in the in-game chat or metagame is whats at issue here: sending other people messages to insult them, throwing matches on purpose to "get back" at your team, being a poor sport, etc.

Edit: Here's an analogy. Consider if you were playing a basketball game and one of the players slapped the ball out of his teammate's hand and started screaming in his face about how he s a terrible player and should have been aborted. That's the sort of behavior we're talking about.

"This is a video game, not real life."

Doesn't matter; you're interacting with real people.

"So the hostility doesn't have any of the harm that we associate with real-world hostility, but occurs within a video game that is modeled on hostility... and I'm not supposed to be hostile?"

No. You're supposed to be a grown up. Especially if you work for the company making the game, and are a public representative of that company.

> This is a video game, not real life.

Games and play is not only human. If you observe puppies and kitties playing, you'll find out that they are mimicking hunting moves, fights, etc., all things they'll do "seriously" in their adult life in order to survive and reproduce.

Kids games are no different. IRL games and video games are no different, except that anonymity allows people to abuse others more.