Unless of course something is agreed upon before (With the subjects, producers, etc.). The documentarian (pretentious but necessary to say lol) just tries to tell the best story possible, whether it's true or not it doesn't matter (Most documentaries are biased and/or skewed, editing in it's self is skewing it). Somethings don't need to be put in documentaries but there's no obligation to anyone, it's just bad creative choices.