So Horn and Raskin are liars? They hold the patents on much of the GUI paradigm used by all computers today. I'd say that gives some weight and provenance to their comments.
Their statements are corroborated by many other sources, Kelly. If you won't believe the "horse's mouth" then you can go on and believe the myths you have been repeating. I lived through this time and was involved in computers and have talked directly to some of the people involved.
Technology is always built on the shoulders of those who went before.
Most people think that XEROX's PARC invented the Mouse. Nope, Douglas Engelbart at Stanford Research Institute (now SRI International) invented the Mouse in 1964, PARC people invented the use of a ball to transfer movement to Engelbart's wheels - an improvement that overcame some shortcomings in Engelbart's design:
Engelbart's Patent Application Drawing
Xerox didn't even invent the GUI, PARC's work on the GUI was built on research borrowed from SRI's work, which was built on a government project called SAGE... which in turn was built on ideas from Ivan Sutherland's Sketchpad which was built on ideas from Vannevar Bush's MEMEX project... and probably built on something Leonardo Da Vinci drew back on the mid 1500s. ;^)>
The PARC people did phenomenally creative work... unfortunately not appreciated or backed by the Xerox management. But so did the people at Apple who were working on turning out a viable product... and succeeded phenomenally.