I am told because blacks have such tightly curly beards with such thick whiskers, they get ingrown hair horribly, and shaving can give some black men horrible follicle irritation. Its a genetic thing or something.

The whole reason the army bans beards is entirely due to the fact they can interfere with gasmasks. That and some operators like pilots need to fit their oxygen masks. Before WW1 it was common for armies everywhere to sport some epic facial hair.