I definitely agree with you that the EMOTIONAL TRUTH is the central reality for any story that's based on historical fact. Even if you're talking about a documentary, any history is itself a fictionalization of reality (see Hayden White, Tropics of Discourse). You can minimize the fictionalization (as Frederic Wiseman does in his documentaries), but you can't eliminate it.

Since the filmmaker is fictionalizing reality, it makes sense that the only true anchor is the emotional truth of the story.

The igloo in "Nanook of the North" had to be constructed for the filming because a camera couldn't fit into the real igloo.