Why does the Super Graphic not have a rotating Viewfinder or Vertical Masks to go with the rotating film back?

Gooooood question. I can only guess that it would have cost more money and they were already competing with rolleis and Hasselblads and losing by the time the Supers came out. The verical masks are a good idea, but only with longer lenses. It wouldn't work for normal lenses, as the vertical apertue would be smaller than the horizontal one.