Because the Rossifumi are too obtuse to know it's themselves that are the joke. Yellow horde types all remind me of a drunk in a black-out at a party who goes around banging into the furniture, saying things he thinks are witty, never realizing that everyone one in the room is rolling their eyes thinking how pitiful the guy is.
That's only the second time i've see the use of the word 'obtuse'..the first was that film 'The Shawshank Redemption',,great film by the way....i reckon you yanks must like that word??