In PostScript level 1, Adobe's fonts were hidden because they didn't want people pirating copies instead of paying for them. That's why you can't do a pathforall on a charpath.
PostScript Level Two has removed the restriction, in the words of the new Red Book, ``for most fonts''. There will still be some vendors who will want to restrict access. Japanese font vendors, for example, are concerned about piracy - given the work that goes into an 8,000-character Kanji font.