I don't think that is what's going on. I work upper body plenty, just don't eat to bulk and that gives me shape not size. Probably most women who do lift are working upper body, and just not bulking.

I'm too lazy to look up actual studies, but I know that inferring from a singular POV will not yield meaningful enough info to claim that a whole gender is not supposed to or doesn't do something regularly unless there is a reason that you can infer something as bold.