I may be going against the grain in this thread, but I think large sanctioning bodies can - they often do not, but they can - exert a positive influence on martial arts. Although school and instructor quality can certainly vary even in large associations, generally, I feel that enforced standards present in some organizations improve the overall quality. In a stand-alone school, I think bad habits and poor technique can continue more easily than if students and instructors have some regular contact - in the sense of "supervisory contact" - with other schools and other instructors.
Having said that, I also have had very poor experience with larger associations, when there is no oversight and no guidance (in terms of actual karate), but only cooperation in terms of large events, basically ways to raise money and attendance, things like that. So, I'd call sanctioning bodies a mixed result.