Comic books, original paperback books (crime/detective stories, westerns, science fiction, etc.), hip-hop,... all intended as disposable entertainment—the commodified, created content of its day.
These forms of media were work-for-hire projects owned by the publisher, paid at a rate per word or page. Assignment turned in and paid for (or not) and on to the next assignment. A volume game.
this is definitely true for genre fiction, especially when pulp magazines were still in business.
That doesn't preclude quality from coming out of it eventually - one of my favorite examples is Walter Miller's 'Canticle for Leibowitz' which was reworked from several of his pulp short stories into a single novel. It's a really great book! I think the incentive structure encouraged volume over quality, but quality still did matter. There wasn't the same algorithm-hacking incentive at play, and you still had to get your works past an editor and approved. Those are important distinctions!
that said, as an aside, im a little nonplussed by the inclusion of hiphop as opposed to, say, 'pop' or 'country', music.
I agree with you on hip-hop. It's very important to me. And it's great that it's become so ubiquitous. But it wasn't always like that. Early hip-hop was just music created extemporaneously at a party or a park jam. It wasn't even recorded. It didn't fit the format of "about 4 minutes and some seconds." And the whole mixtape era was music of the moment, not even an official release, mostly a promotional product.