Yeah because a massive beard has helped glass jawed jokes like Brock Lesnar and Kimbo Slice tank shots to the face with ease.
Hell, a really thick beard didn't help Duran either. Hearns still knocked him out. A beard doesn't really add that much to punch resistance. If your chin sucks or you're hit square by a concussive puncher, you're going down, and a beard isn't going to keep you up. The only possible defensive advantage of a beard is that it might make punches glance or not hit clean as easily or as often, but how often do you ever see punches glance or slide past Pac's face? Just doesn't happen. He either catches punches with his gloves, ducks under them, or gets tagged clean. He doesn't roll with punches, so having a beard doesn't even help him in that regard.
Pacquiao has a very strong chin but doesn't like it to the body as much. He was KO'd twice as a much younger fighter; once by body shot and once when he was drained. Since then, he's taken head shots extremely well.
Then again, I don't expect you to just accept logic. You thought Josesito Lopez had Canelo Alvarez right where he wanted him and the fight was stopped prematurely you re****ed disgrace