Warning: Lots of cursing ahead - mostly for explanatory purposes. TL;DR hogwild is right. I posted based on article title. FPS gamers are mostly angry teens. Other games exist with a more mature player base.
That said, the original researchers picked Halo 3, which is going to be popular with the teenager crowd, just as any FPS is going to be. CoD, Halo, CS, TF2, etc. are going to be largely dominated by the young teen to young adult crowd. They're probably guys and they're probably assholes. Combat is fast-paced, reactionary, and most people aren't worried about employing any real strategy. It's spawn, run, spray, and die. People are amped up and very hostile to friendly and enemy players. If you're better than someone, you're a no-life cocksucker who lives in mom's basement. If you're worse, then you're a scrub-ass retarded bitch. That's probably about 75% of the people I get matched with in CSGO. The other 25% either don't talk or aren't assholes when they do. Totally pulling these numbers out of thin air, but that's my guesstimate based on nearly 900 hours in CSGO alone. I personally am much more hostile when I play FPS over other types of games. I found one of the alternate explanations for hostility towards females the most plausible. It's a novelty to have a female actually talk in-game. It's like turning on a bug zapper or shooting off a flare. Everyone's been calling each other a faggot all day, but now there's a female here! We can call her a bitch or a cunt! It's new and exciting! I don't at all blame females for staying silent on the mic, or staying in alternate communication programs with their friends. I've witnessed maybe 2 or 3 games ever where the female didn't get hounded by people calling her names or dudes trying to get e-laid (or whatever the point of trying to hit on females on a game is.) Do this study with RTS, TBS, or 4X games and I imagine that you'd see a much different story. My only real data point on this are Scarlett and puCK, two professional StarCraft II players that are widely loved by the community. They're both transgender, and though you'll see a few hateful comments, both players have displayed such vast amounts of skill that nobody can really say anything against them. My hypothesis is that these games are focused on individual rather than a team effort, so the blame for winning or losing is resting squarely on the players shoulders. From my experience (~15 years playing StarCraft and StarCraft II) most players are more relaxed and simply don't care if you're male or female. You're either good or bad and your skill is what you're judged by. Maybe it's the people I choose to hang out with, or I could be very biased, but that's what I've found to be true in the vast amount of time that I've sunk into gaming. I think that I just don't want everyone in the gaming community to be viewed the same as FPS players. We're not all basement-dwelling neckbeards or tweaky 16 year-olds hopped up on Mountain Dew and Cheetos. Edit - I also really don't think that the researchers got to rank 50, or even played with rank 50 players in only 163 (I think was the number) games. Teammate response to prerecorded messages is also going to be much lower as you advance in rank because your team expects you to actually make accurate callouts.
Admittedly, I didn't realize that the article contained a paper. I just read through it between rounds of CSGO and it wasn't until hogwild mentioned the paper that I went back and read through it. I wrote my previous comment based on the title and content of the article and not the actual paper. After reading through the paper, I don't see the researchers attempting to apply their findings to the entire gaming community. In fact, they mention trying to use games as a learning opportunity to show that being bested by a female isn't the soul-crushing experience that men have evolved to believe it to be. I don't disagree with their findings for FPS games. They're certainly accurate based on the type of game they picked. However, I don't think that they quite understand that the gaming community is actually many much smaller communities that are all grouped under the umbrella of "gaming." I also don't think that people see themselves in a hierarchy where they are either dominant or submissive, but I do understand how one could come to that conclusion.