I’m not saying this explains all of it, but there is a lot more resistance to the mainstream culture now than in previous decades. That culture is the continuation of Roman Imperialism which is where shaving the face is adopted from. This was in contrast to other societies such as the Greeks and Vandals.
Of course not everyone wearing a beard is counter-culture, but the counter-culture is currently strong enough to influence acceptable trends. Looking like Zuck isn’t cool anymore. I would say this trend started many years ago with the hipsters, and has steadily expanded beyond that group.