The discourse surrounding films tends to isolate
documentaries from basically every other kind of production. Sure, there are
mockumentary hybrids that blur that line, but overall, people expect a degree
of facticity from documentaries that isn’t normally expected (or at least expected
as much) of fiction or even fictionalised versions of real events.
Considering how the nature of filmmaking involves a certain element of
constructing reality in its very process, that facticity isn’t always
guaranteed or even aimed for. But every so often, a documentary takes this idea
on-board and basically turns into its own statement on what makes a documentary
qualify as such.
