Who makes this odd rule?

Gerard Vanderleun links to a post by Ace of Spades in which Ace questions why it is not okay to call Marxists Marxists.

if you note that Marxists are indeed Marxists it's supposedly a sort of Hate Crime up with which we must not put. Who made this odd rule? Would I be correct in guessing that Marxists themselves created it and Marxists themselves (and their fellow travelers) are the major proponents of it? The only objection can come from the Marxists themselves, who prefer to work in secret, and the Democrats, who prefer their alliance with the Marxists not be noted, lest it embarrass them politically. But Marxists, and the left, and the Democrats, and university professors, and the leftists that control the media, all line up to a man to insist it's Foul Play and Creeping Fascism if you say something True. So: Who are the fascists again?

read more here: http://minx.cc/?post=337844