Some people DO get angry ingame for certain things, which I'm not sure what Silverbat means, but it makes more sense when you look at it a certain way. There are people that do get genuinely pissed if they lose out on a NM spawn, and will get depressed if they can't find a party. How do I know this? Because it's quite easy to lose yourself in the game and become totally immersed in the world of FFXI, especially if there is no other social outlet in your life.
It's pretty simple, once you think about it... if there aren't any people to accept you or share time with in real life, you're going to turn to the next best thing, which is the virtual world. It turns out being a viscious cycle, as people who aren't satisfied with their lives will put more stock in the game, and if they can't get satisfaction out of the game, it could either make them strive to get out of their hole in real life to achieve satisfaction, or it could drive them deeper into the virtual world, pretty much shutting out the real world. I guess keeping your real life duties and stuff you want to accomplish in the game balanced is the best way to go about it, but it's obvious it's easier said than done.