That "all three use Display Postscript, CoreGraphics and Quartz" doesn't mean they use the respective drawing context as it's intended for screen/print work.
Editing LaTeX with Vim on a Mac also uses Quartz to render the Vim window, that doesn't mean that you get what I talked about.
With respect to your examples now, HTML and ePub/Mobi don't guarantee they are WYSIWYG and stable between different viewing devices and contexts. On the contrary, for example even something as basic as the line width can change by making your browser or eBook reader wider.
That said, they are not the standard output of WYSIWYG editors we were talking about either (despite some WYSIWYG editors being able to save in those formats too).
Word, Pages, Open Office et al have print view modes that look identical to what will be printed. As do programs such as InDesign, Quark XPress, etc.
Editing LaTeX with Vim on a Mac also uses Quartz to render the Vim window, that doesn't mean that you get what I talked about.
With respect to your examples now, HTML and ePub/Mobi don't guarantee they are WYSIWYG and stable between different viewing devices and contexts. On the contrary, for example even something as basic as the line width can change by making your browser or eBook reader wider.
That said, they are not the standard output of WYSIWYG editors we were talking about either (despite some WYSIWYG editors being able to save in those formats too).
Word, Pages, Open Office et al have print view modes that look identical to what will be printed. As do programs such as InDesign, Quark XPress, etc.