In the 19th century, when Dewey created his system, fiction was viewed with disdain as disposable fluff. "Real" literature was poetry, and "real" books were nonfiction.
That hasn't really changed much.
During the course of my four semesters of Short Story Workshop at a local junior college, I had an ongoing friendly debate with the professor in which I asserted that (1)
all fiction is genre fiction, because all fiction has a genre, even if the genre is "contemporary realism" or "historical realism," and (2) the distinction between "popular fiction" and "literary fiction" is completely artificial, because there is very little fiction that wasn't intended to be popular.
Consider music by analogy. Now in the 20th century, there
is a fair amount of formally-composed art music that was intentionally written to be off-putting to the general public, or to casual listeners, because it was written for an audience of jaded, pretentious, elitists who cared more about excluding outsiders than they did about actually understanding or enjoying the music. But how much Schoenberg, Stockhausen, or Cage gets airplay on typical classical radio stations (outside of special-interest programs concentrating on new music)? I have a strong recollection of remarking to a total stranger, during intermission of an Orange County Chamber Orchestra concert, that a moderately challenging piece just performed was new music, but far from inaccessible. He denied that it was new music. The composer was still alive; it was not written for film, nor for musical theatre, but for the concert stage; the ink was barely dry on the manuscript score.
I suppressed the urge to strangle the guy on the spot.
Bach wrote mainly for church services. Handel, Haydn, and Mozart wrote for wealthy patrons, and for popular entertainment. Beethoven wrote for everybody. None of the sixteenth through nineteenth century composers we classify under the broad sense of the term, "classical music," deliberately sought to be unpopular. We classify them that way because their music stood the test of time, and is now seen as timeless. And there is a great deal of contemporary commercial popular music that cribs musical ideas from classical pieces (and a great deal of it that is now considered classical, e.g., Gershwin's
Rhapsody in Blue, various early Broadway musicals, and Prokofiev's film scores).
And that is even more true of fiction. People may write intentionally unpopular fiction, but it rarely gets published, at least on a royalty basis, because
publishers are in business to make money by selling books. The late, great, Dr. Karl Haas, in explaining the title of his long-running series of radio broadcasts,
Adventures in Good Music, asserted that there are really only two kinds of music: good and bad, and they are entirely independent of genre. And by way of a corollary, I would add that there isn't a whole lot that can be objectively called bad. The same is true of fiction. I've read
exactly one book that I regard as so unspeakably and irredeemably bad that I refuse to share its title in a public forum. And it was self-published.
Now there are a lot of books out there that only get bought (or checked out of the library) if either (a) it's a required reading in a literature class, or (b) somebody is buying it in order to support an elitist pretense of being "cultured." And there are also a great many books and short stories that are extremely worthwhile, that people only get introduced to in the classroom (Shirley Jackson's "The Lottery," with its brilliantly subtle foreshadowing that telegraphs nothing about the shocking ending, and Robert Coover's "The Babysitter," that shifts to a different reality with each new paragraph, both come to mind, and I've written an ultra-short that riffs on the experience of being a "Lottery virgin"). And there's also an awful lot out there that's eminently forgettable, and/or instantly dated.
Certainly fiction that makes the genre serve the story is superior to fiction in which the story is the slave of the genre. The former enriches both story and genre, while the latter impoverishes both. But to declare that whole genres of fiction are unworthy of a call-number, or unworthy of having a call-number that acknowledges the genre, is nothing but elitist
bovine scat.