I am a counterexample. I learned how to write in college during my freshman year. My professor capped all essays at 300 words which, at first blush, seems like a cakewalk. I found it much harder to get a point across in 300 words than all of the previous reports I'd written where the objective was to fill pages.

Filling pages is different from writing. The most frequent criticism he'd levy was "show, don't tell".