All Films are Documentary Films
Technically, all films are shockumentary films, but…
At a more basic level, all films are documentary films.
Is Star Wars really about a young man joining an intergalactic rebel force?
Or Is Star Wars actually about the motion photography of highly-crafted analogue spacecraft models being blown up for real in front of a lens?
Is Boogie Nights really about a dude making his way in the porn industry?
Or is Boogie Nights actually about non-stop expertly-coordinated camera movements?
As a filmmaker, your style will vary dramatically based on what you think about this subject.
It is my belief that the documentary impulse of cinema pervades all genres, and is the equivalent of the “sketch” underneath the painting.
Documentary movies are an extension of this impulse — but the documentary impulse is principle in all films. Movies are about capturing a moment in time. That “freezing” of time is not a by-product of the medium, but the medium itself.
Consider when you watch an old noir from the 1940’s. None of those people are alive anymore. Many of those locations are long gone. Even the burgers they fry in diners are made of totally different ingredients than they are today. Heck, even the babies featured in the movie grew old & died. Nothing in those movies exist as they appear in the movie anymore due to the ravages of time.
And so when we look back at these films, we can see that the capturing of the celebrities / dialect / locations of the 1940’s is actually a principle spectacle in the film, and not something that happens after the fact or “on top” of the story.
Other colleagues of mine believe this documentary impulse is either a) an intellectual concept only & not present in narrative films; or b) an ornamenting after-thought & not the primary impulse of cinema.
There’s no way of proving this. It’s simply a matter of taste. I just believe my taste is right lol.