It’s not stupidity, there’s a reason no one in the military is allowed to have any facial hair other than a mustache and you have twice a day in training, you never know when us sneeky cadre will lob a can of CS at the recruits to test their skills of masking up effectively. Same shave schedule on active duty in an area where chemical or biological weapons might be used. Unless you are socom then opsec and blending with the locals might mean facial hair but they are not expected to survive a gas attack anyways.
Masks do not seal around facial hair. This graphic is years old they just posted it again. Fun fact oil rig workers also cannot have facial hair in areas where H2S gas might be found the breather masks won’t seal and you will be dead after a few breaths or less of H2S I have to shave every third week if I’m on rig rotation just enough time to grow back a full beard only to cut it off.
A Prohibition against facial hair is perfectly understandable and entirely logical. A chart with 43 different kinds of beards and what they are called is inane. I am going to assume that that poster was not issued by the CDC, is some chart of something that appeared on a magazine somewhere and a trusty fr Forum member posted it as a funny.