Oh man, people don't even know what a bad community is until they've played DotA. I was really into that game for a few years, and I still think it's one of the best games ever made. I tried to get my wife into it, and it just wasn't her thing. Her only match, though, was filled with tons of people raging at her, telling her to "get the fuck out of the game", etc. Yeah, she went 0-13, but she was still learning the buttons!
She thought it was absolutely hilarious, just like your friend did. After a while, she started typing "lolz" every time she died. Of course, my wife is also one of those people that would sit in Barrens chat in WoW just to talk about Chuck Norris - she is an odd and lovely bird.
My first DotA match was abysmal. All 9 of the other players were pissing on me for any mistakes I made, and I didn't even understand what the point of the game was yet. I fed hard, no doubt, but no one tried to teach me anything. Luckily for myself, I'm an ardent self-educator when it comes to gaming, so I learned a lot and did well. But even as someone who had gone Beyond Godlike with 80% of the characters in the game, I still had bad matches, and the rage and spittle was always there.
Oh, and if you happened to be grouped with one of the self-righteous assholes that thinks he's just the best DotA player ever, god help you if you happen to "steal" one of his kills. He'll grief you for the rest of the match for "losing the game" for the team. Or he'll intentionally not help you if you're being ganked, or will just sit around and KS you for the rest of the game.
Ugh.
That joke had the Dennis Miller Ratio going for it.