In his autobiography,
Stefan Zweig gives two arguments for beards, specifically for Austria in the very late 19th and beginning 20th century:
1. To make men look older, or to obscure their youth.
This seemed to refer primarily to Austria. He describes at length how Austrian society was all about stability and reliability; youth was a sysnonym of potential trouble-making ideas, while old age promised "experience" and calmness.
2. A more universal argument:
Everything reminding of sexuality was usually hidden. This included (though mainly for women) the obscuration of all bodily details (quotation: "A bridegroom could not even remotely guess the physique of his future companion during the wedding dinner; he could not tell whether had grown straight or buckled, whether she was long- or short-legged").
So this rose the question with what to cover all individual details. And fashion selected a caricature of a standardized man and of a stan woman respectively which all had to converge to. This involved a corsaged wasp waist for women, and voluminous beards for men.
Ironically, the timidity of everything sexual lead to underlining sexual attributes.