I would argue there is some recency: it used to be the case that editors were working with authors in the sense of building their careers. Not even 10 years ago it could be expected an author might not hit it big until their 3rd or 4th book (George RR Martin was like this) and editors were focused on building the skills of their authors in storytelling. Now editors are also pulled in a billion different directions and work more like project managers on way too many books at a time, and things like typos and whatnot are being introduced into traditionally published books with glossy special edition covers.

Also, quantity is a quality in and of itself.

Grocery store softcore porn was still very expensive in time, money, and space. The amount of energy required to move a book around is monumental in comparison to how much energy it takes to move the same number of bits of information contained in the book. The speed at which just the information moves (in modern digital networks) is nearly instantaneous. The space the digital book carries is not measurable by the human senses.

It was nearly impossible for most people to afford to fill every waking moment with a book in front of them, bar a few addicts. Now there is a river of information actively fighting for your eyeballs at every moment. And how the meme-gene works, the most addictive types will rise as the victor.