This struck me as analysis for the sake of analysis. I'm willing to wager many people pick the most bare wall in their house on purpose because it looks best to film against.
People pick bare walls because they're imitating each other, and the bare-wall look is easy to recreate. For example, Hannah Hart can make videos like this https://www.youtube.com/watch?v=OzYk2iOZqss#t=242 but when she built a studio, it looked like this https://www.youtube.com/watch?v=gjK2xgolAws The first one is more engaging, but people have this idea of what a youtube video looks like, and they just keep doing that because it's what they're used to.