People tend to think about other people in groups. But groups are nearly never completely homogeneous. Thus every possible statement you can make about "bankers", or "soccer fans", or "hardcore gamers" is most certainly wrong for at least part of that population. Much of this is due to a rather necessary brevity of speech: If you want to occupy Wall Street and protest against banker's salaries and/or behavior, your sign can't possibly be big enough to list all the possible exceptions to the term "bankers". Thus on my blog, if "hardcore gamers" are mentioned, I do not list all possible exceptions either. I am absolutely sure that there are some hardcore gamers which are very nice people, and who spend their time patiently helping and teaching new players. Likewise I am convinced that there are honest bankers, and quietly polite English soccer fans.
Thus it might appear unfair to some that if you watch any documentary about hardcore gamers raiding in an MMORPG, you will always see some not very attractive, nor very well kempt guy shouting profanities in his headset. Hey, you will say, not all hardcore gamers are like this! And you are right. But does this make the documentary wrong? Haven't we all met that guy and heard his shouted profanities over Teamspeak? Haven't we read those blog entries where some hardcore gamers declared their superiority, and stated how unworthy other players were of "welfare epics" (which incidentally is a term that was used by a hardcore gamer working for Blizzard and speaking in an official capacity)? Haven't we all seen the general chat in which hardcore gamers measured the worth of other human beings by their gearscore, and called less good players by all sorts of names?
If any sort of behavior is sufficiently prevalent and sufficiently offensive in a group to be widely remarked, it is inevitable that even the members of that population that don't behave like that risk getting tarred with the same brush. The French town that had several pubs demolished by English hooligans after a game will *not* remember the quietly polite English soccer fan. And the average MMORPG player will be more likely to remember the hardcore gamer who called him names for having gemmed or enchanted one piece of gear wrong than some other hardcore gamer who didn't behave badly. Unless there is a certain degree of self-policing in a group, where certain ethical standards are adopted, and members are clearly told that certain modes of behavior aren't acceptable, this sort of generalization is likely to continue. There are lots of examples of such wider groups who made an effort to become more respectable and succeeded. But it requires more than just denial or anecdotal evidence of a few group members having done something nice.