By “non-fiction” I mean mass-market non-fiction, those paperbacks with titles like “Sleep: Why We Need It, And Why We Don’t Get Enough of It”. Textbooks and technical books are a separate category.
The problem with non-fiction, and the reason most non-fiction books are not worth reading, is the interests of the reader and writer are misaligned.
The actual text of the book—the semantic content—doesn’t matter to the writer. If you read a few of these books, you inevitably notice the patterns: every chapter begins with an anecdote, or with a time and place and a person, to humanize the topic; the tone is didactic, condescending, similar to the voice of authority; every book feels like it was written by the same bloodless person. The book’s real content is a one-page essay that has been mechanically expanded to publication length, and filled with irrelevance. The reader wants the essay: something novel and useful and brief, because few things are worth elaborating to 200 pages, but the writer is not incentivized to provide it.
If the text doesn’t matter, what does? The press tour, the interviews, the readings in libraries followed by a Q&A, the excerpts of the book that are published in literary magazines, the reviews published in famous newspapers.
Writing a non-fiction book is both a means to increase your social status and a way to become intellectually legitimate: someone who can be cited as an authority, someone whom journalists can quote. What separates a crackpot with a blog from an intellectual authority is the latter has had their work published by a legitimate publisher and reviewed by a legitimate newspaper.
Dually, a writer who self-publishes non-fiction on Amazon or Gumroad, and whose reviews come exclusively from normal people, will accrue some social status, but they will not become an intellectual authority. Like the photoelectric effect: a million five-star Goodreads ratings are less than a blurb from The New York Times.
Why does this matter? Because we have too many books already, and publishing as a status play pollutes the information environment.