The point is less about body shaming and more about shaming the person's "small dick energy". Eg the kind of behavior you'd expect from someone who thinks dick size matters a ton and would buy nice things to try and compensate for their lack of size.
Hmmm. I feel like one of those words is far more charged than the other, but I agree that it'd be nice if we had better alternatives. The problem is that it's making fun of a certain specific attitude that some men have that tends to extend to high levels of care about the size of their junk, and there's not quite an equivalent concept for another topic. I mean, it's basically a way to call someone "insecure about things about yourself that you can't change or control, so you spend your time grasping at whatever material gains you can in order to try and have some semblance of Identity beyond those insecurities".