I dunno about survivorship bias. Some of the books I've been re-reading are out of print and hard to find. In any case, I'm not saying the best books today can't hold a candle to what was published forty year ago. Not at all. The remains as it was. But you have to understand the changes that have gone on in traditional publishing. Yes, ebooks are a big deal, but an even bigger deal is print on demand.
It used to be that publishers had to take a big risk publishing anyone who wasn't an A-list author. The way it worked is that the publisher would do a big print run. They'd send cases of the book to bookstores, who'd put them on the shelves. After awhile if all the copies didn't sell, the bookstores would ship back the unsold copies and the publisher would pulp them. All very expensive.
It doesn't work that way any longer. It's now feasible and affordable to do much smaller print runs, and bookstores can order a few copies of a book, then if those copies sell order a few more copies. This has two big effects. First, it's a lot less *intrinsically* risky to publish an author than it was ten or twenty years ago. This means you don't need balls to be a publisher these days. You still make money on the blockbusters that fly off the shelves, but you can also make money on a mediocre, me-too book.
The second big effect is that bookstores can stock more authors. All things being equal, that should mean there's a lot more diversity in books on bookstore shelves -- but there isn't. Instead there's more authors doing more of the same. And these second tier authors are not by any means *bad*. The craft standard for these stories is very high, probably higher than run-of-the-mill stories forty years ago. It's just that as a whole it's more of the same old thing.
This isn't the author's fault; an author writes whatever appeals to him, then tries to get an editor to pick it up. It's the agents, editors and booksellers who selectwhat the public finally sees, and by in large that is well-crafted stories that bear a striking resemblance to some blockbuster franchise. This is not because anyone expects to duplicate the success of the Sookie Stackhouse or Twilight stories. They know quite well that's not going to happen with a "me too" story. What they're looking for is something that can sell a modest number of copies to fans of the big franchises and turn a small but reliable profit. That's a strategy that wasn't possible twenty years ago.
Movies of course are looking for blockbusters, but the essential similarity is that the producers are often combining well-known elements in an attempt to generate sure-fire profits.