When I was growing up, beards and facial hair was still mostly for people we associated with being 'rugged' or outdoorsy (think Brawny Man). As I got older, that trend became way less associated with that and now you see men of all creeds and types sporting them.

Folks from all around the globe and across time have gone back and forth on hair and beards too though. Ancient middle east civilizations saw long, well maintained beards as a sign of royalty and prestige, wild and unkempt beards were not favored. Rome, at one time, saw beards as barbaric and was big on being clean shaven, but even they eventually embraced the look. Sometimes beards can relate to and reflect religious values (judaism, islam, sikhism). My great-grandfather was an old school southern church-goer type and would shave every day; he thought beards were gross and reflected how you were as a person. My grandfather were a beard to hide scars from a motorcycle accident he had at 15.

Long story short, lots of reasons to grow and maintain facial and it is hard to say any single, unifying reason. I would not say it is exclusive to any one group anymore. It is just a fashion/men style trend and, like others, ebbs and flows in popularity.