Earlier quoted context omitted.
It's probably confirmation bias. Same reason a study with positive outcomes about coffee/alcohol/gay parenthood/gender reassignment/ are not criticized as much as a study on the same topic that had negative outcomes. We want certain things to be true so we (consciously or not) avoid criticizing studies bolstering what we want to be true and harshly criticize studies we want to be false. I like to think science always…
I mean, part of this is probably also some degree of us intuitively knowing the answer. If you have a friend group of 10 people, 4 of which regularly work out. You will probably notice that those 4 friends have less body fat and are more toned than the other 6. At that point, if a study came out saying that working out had no impact on body physique, you'd reflexively question the results. That might sound ridiculous…
And yet gamers remain relatively docile on the whole. And while they may get heated their debates about PlayStation vs XBox are about as likely to result in fatalities as the programming community's vim vs emacs or tabs vs spaces debates.