I've been here 8 years and worked in IT for several of those. Definitely get the "hard work" ethic, but I feel like your post takes an overly cynical/narrow spin on it.

In my own limited exposure, most designers I have encountered worked by feel and experience instead of analytical principles. I've definitely heard people say that a part of the page feels a bit empty or get some evaluation to that effect from peers. It's much rarer to hear someone say something looks too busy or crowded.

I suspect that in the long grind to "polish your work", there's a simply tendency to remove all these "empty feeling" spots more than to "trim the fat".

This reduced the problem to why there's a bias for things to feel empty instead of busy. To venture a bit of personal sociology here, my experience makes me feel like Japan produces a bias toward more intentional and deliberate behavior. Or worded less charitably, we could maybe call it fussy?

Accepting this idea, in web design we'd expect a bias toward needing deliberate explanations for every aspect of the page layout, including every bit of white space that someone might point out.