Now, I'm a Texan, and as such my meat sensibilities are far more honed toward BBQ and tamales . . . but what I have experienced of cheesesteak sandwiches suggests that the "steak" part of the title is relatively accurate.
That given - at the very least, that the steak in cheesesteak is decent meat - why the HELL would anyone pollute it with the abomination that is Cheez Whiz?
An excellent question, my Texas friend.
Should you ever make it to Geno's, you'll be happy to know that you can order or cheesesteak made with American or Provolone, as well.
(Amazingly Cheez Wiz, though an abomination in or on all other things, works better than you'd think on a cheesesteak. Geno's is open 24 hours, so another key may be going there at 3 or 4 in the morning.)