Alaphilippe and Roglic have handsome faces without moustache. Maybe they grow moustaches to look terrible, to not go to the discotheque, not go partying. David Millar once explained he cut away all his hair, to look ugly. So he didn‘t have to go partying, and could concentrate on his training.
However, if you have nice hair, you'll simply be dragged to the parties, nothing you can do about it!