One of the subtler ironies of Amazon's creeping approach toward a veritable monopoly over the book market is the way in which unspoken Web conventions make bibliophiles complicit. When you write about a book, particularly one with which your readers may not already be familiar, it can be both convenient and helpful to link to some resource about it. For many sites, the destination of choice — or, at least, of convenience — is an Amazon sales page. Amazon has encouraged the convention with incentives like its affiliate program, which pays site owners for the traffic they send to its pages.
The resemblance of that quid pro quo to other forms of advertising has occasionally created controversy (as, for example, in the case of Brain Pickings), but the habit of treating Amazon as a kind of Wikipedia for books is problematic even when the link-creator gets nothing in return. "All roads lead to Rome" is not just an appraisal of the ancient department of transportation; that network of highways also ensured that most commerce in the Empire eventually wended its way back to Rome. Similarly, the more we spread links to Amazon across the Web, the more insistently we're all led back to the site. Whether or not the person creating the link gets paid for the courtesy, the convention of sending readers to Amazon to learn more about a book plays into that strategy. Affiliate links recommend specific purchases, sure, but arguably the bigger benefit to Amazon is omnipresence.
The antidote, of course, is to link deliberately — that is, to link to Amazon only when your conscious goal is to deliver a person to Amazon. If you only want to direct your readers to more information about a book, point them somewhere else. But where? We default to Amazon in part because it's built one of the most exhaustive catalogues of books available. Writers who eschew the behemoth have sometimes gotten around sending traffic to it by linking to "social" book sites, like Good Reads. That's only a viable workaround so long as Amazon doesn't swoop down and buy Good Reads — which, of course, it did earlier this month. The future's a little fuzzy for Good Reads, but for now it's a safe bet that Amazon wouldn't have bought it if it didn't have a plan for converting its traffic into sales.
A better, more direct solution, it seems to me, is to link to the book's publisher whenever possible. Barring that, link to a solid review. Both of those require a bit more effort, but then, Amazon is counting on us defaulting to convention.