It was a limited edition book printed "for subscribers" in 1931. My theory is that the publisher didn't have a title on the promised schedule, so he panicked, plagiarized some chapters from some dead guys, and printed and mailed it to subscribers as a "new book." Easy for him to do. Nearly impossible for readers in 1931 to uncover the deception, but fairly simple for me to figure out (if laborious) now that a lot of historical content is searchable online.

Generally, yes, I think authors and publishers should reveal the degree of fiction in their stories.

In recent years, several memoirists who went on the talk show circuit with their "memoirs" landed in hot water when it was revealed that they were faking their life stories, i.e. they weren't really Holocaust survivors, drug addicts, etc. but wrote stories looking for sympathy.

Similarly, people who fake their career resume are writing a one-page fiction, I guess!