Part of the problem is trying to be authoritative with broad conclusions. You can have a documentary cover a story or a person's life while being thorough and entertaining, but things like an overall industry's practices are just too complicated to go over quickly. People are going to have lots of varying experiences with it, and just giving facts about it misses human elements that allow people to imagine being there. It needs to be a story, but just one story also can't apply to everyone.