Even if they do research it's a vastly different context. <70s was niche and rich. Nowadays it's for the mainstream. I recently learned that Xerox GUI had an OO copy function. A generic one, for any object. When Jobs and Gates took the GUI, they mostly brought the metaphor, not the underlying ideas.
Star also designed the mouse to be used with the keyboard, rather than instead of it. The generic object functions were arranged to the left of the alphanumeric section, to be used by the left hand to operate on the object selected by the mouse in the right. They had a column of wide keys for the main object operations (DELETE, COPY, MOVE, PROPERTIES) and a single-width column further to the left with secondary operations (AGAIN, FIND, SAME [copy properties], OPEN).
They also did not have an invisible clipboard. COPY meant what today would be copy+paste, and MOVE, cut+paste. If you wanted a 'clipboard' document it would be manifest and direct like everything else, and you would COPY or MOVE things to and from it.
IIRC in a demo they were copying a UI element, a whole panel or a window. It felt like a live object playground. AFAIK other OSes where limited to semi-type strings.
Nope, it can be used for general data. On OS X (since that's what I'm most familiar with) you can put any data you want on the clipboard, and even list the types that you can provide it in, so when it gets pasted, the target can specify which format they want it in.
For instance, copying and pasting files to duplicate them is a common operation on many operating systems.
