The key here is to acknowledge the difference between "expert knowledge" and "incidental knowledge".
"Expert knowledge", here on Arqade, is about playing video games. It's primarily about the actual gameplay but also deals with some things like getting things to run or terminology of the system. Point is, what we deal with is primarily as people who are playing games. That's what the expertise of the site is, and what questions and answers here are all about.
"Incidental knowledge" is anything that people happen to know. For example, I know a lot about how to cook eggs. More related to the subject matter of Arqade, I am buddies with various localization groups and so I know a bunch of release schedules, and I also know a few developers and thus can learn why certain people made certain mechanics. Ergo, I exist as a person in this community who happens to know this stuff. That doesn't make it on-topic - because all of this is incidental knowledge that is outside the scope of what the audience of this site caters to. Likewise you can't ask how to make an omelet here - unless it involves corpses that are safe to eat.
What makes a game popular is going to be incidental knowledge. On a player level, people have their own ideas of what they like. The big picture of why a game gets popular is an amalgam of these ideas - and studying what that amalgam is, that extends outside the realm of the players and into the realm of sociology and people study. It at heart comes from the gameplay but the topic itself isn't. So for the same reason that we don't handle news, or game mechanical reasoning, I would say we do not cater to studies of why things are successful.