There must be something in human nature that makes many of us go to great lengths to avoid painful subjects. People in my parents' generation would never mention when someone had cancer ["the big C"], as opposed to other illnesses because it was viewed as a death sentence. My late father in law was mostly silent about his 15 months in a German POW camp after his plane was shot down. Other friends say their relatives avoided discussing wartime experiences because they didn't want to relive any part of them by retelling.
A recent Israeli film makes this point even more powerfully. In "The Flat" Arnon Goldfinger starts filming the sorting through of his late grandmother's possessions in her Tel Aviv apartment only to discover a shocking secret -- evidence that his grandparents had close relations with a senior Nazi official before and even after World War II. Goldfinger's mother didn't know this and admits being reluctant to ask her parents about what happened to relatives who stayed in Germany after they emigrated to Palestine in 1936. He later interviews the daughter of the former Nazi official, who denies any wrongdoing by her father and is stiffly incurious about evidence that might reveal a different story.
I guess we all live in worlds of settled memories, accurate or not. I discovered, when reading some of the diaries I have kept since I was ten years old, that some of my favorite family stories were wrong in key details. I agree that autobiography is just another form of fiction. But I think people will enjoy the deeper meanings provided by this documentary.