If I can navel-gaze about my article for a minute, it occurs to me that I rely far more on a canon in my research on documentary than my research on classical Hollywood. By this I mean not only the films I selected (Helvetica might not be part of the canon but most of my other titles are in some way or another) but also the finite body of scholarship I draw on.
On one hand, I think documentary studies can do more to look beyond the canon. My own research fails to do so partly out of my limitations in time and imagination. Other scholars out there are doing a much better job of thinking outside the canon, though as I've suggested in my essay they often do so by privileging rule-breaking documentaries over ones which might be considered ordinary.
On the other hand, documentary as a field is a self-conscious tradition, so acknowledging the closed circuit of aesthetic reference and influence makes a certain sense. And many documentaries, mainstream and community-oriented alike, do not aim primarily to be consumed as aesthetic objects but as political praxis.