Warcraft 3 is filled with mostly lovely people, and only occasional bad people. All hail RTS, the gentleman's genre. I haven't played Civ 5 online but I suspect there's mostly nice people there too. My small amount of GGPO Third Strike suggests to me that fighting game (or at least GGPO) has a pleasant userbase also.
Also they are angry because they are playing Halo instead of Timesplitters. I'd be upset too!