It would be VERY hard to just pluck off someone’s beard – unless, of course, it were a false one. Many Santa Clauses’ beards are pluck off-able. Many a comedy old man or vaudeville wise man, these could all be easily plucked. One quick tug or lifting the wires that curve round the ears and beard can be yours.
But an actual beard that grows on a man’s face, from a man’s face? It would either take tremendous force or great patience, one hair at a time. And even then, the beard would seem to be plucked OUT, not off.
It might be shaved off but the strength of hair follicles are such that removing it with one pluck, isn’t physically possible.
Given the theatrical tradition of false beards (see also, Bottom’s excitement about choosing his beard for Pyramus and Thisbe) perhaps it’s a theatrical move, this plucking off of beards and blowing it in one’s face.