… IIRC the big thing that turned “clean shaven and buzz cut” into a moral imperative for men was chemical warfare in WW1, and the need for gas masks to seal tightly
Soldiers were still training for gas combat into the 1940s, and WW2 veterans were running the world until the early 1990s
The height of hair craziness IMO was astronauts in the Apollo program having to shave in zero gravity, when surely the safest place for all those little floating bits of beard would have been remaining securely attached to the astronauts’ faces 
