It depends whether your objective is WCAG compliance or some more utopian goal. I would say that providing the native file does comply with WCAG even if it is not the optimal user experience.
As always, context is important. Most of our clients are design agencies who are contractually obliged to build websites that comply with WCAG, so that is what we test for. On the other hand, some of our public sector clients are legally mandated to make their websites as accessible as possible, so they probably would not find the provision of native files to be an acceptable solution.
