Which, of course, wouldn't matter to anyone if it had presented itself as a novel, and may still not matter to readers who find the story meaningful. Books are often not what they seem, or as presented. Forrest Carter's wildly successful The Education of Little Tree (a true story) was not a memoir of a Cherokee boyhood, but a work of fiction. Edmund Morris's Dutch : a memoir of Ronald Reagan was 'told' by a fictional narrator, and some reviewers (and library catalogers) felt it would better be considered historical fiction. Danny Santiago, the hypothetical young Hispanic author of Famous All Over Town, turned out to be an established writer named Daniel James who had been blacklisted in the McCarthy era. Go Ask Alice was not the diary of an anonymous very young teen, but was produced by a woman named Beatrice Sparks. There was never a Carolyn Keene.
It will be interesting to see if the high profile attack on Frey's fidelity to fact will decrease the demand for the book.