The first (and notably pre-digital), yet most profound, step down this road, at least here in the UK, was the death of the Net Book Agreement, which meant that we left a situation where sales of popular works subsidised the cost of obscure/literary/old works. The difference in price between say, a Penguin Classic and the latest thriller would be small or zero, making all paperbacks relatively affordable and accessible. Since then in terms of pricing and on-shelf availability, populism has taken over and "pile 'em high, sell 'em cheap" has taken over, slowly sequeezing out everything else.
Yes, that's precisely the sort of thing I mean. Germany still maintains mandatory minimum price tags for new hardcovers (and a few other items), but as Mike Finn noted in his post on this subject, Amazon has really been a game changer in the market, and that's no different here, either, of course -- and they are the undisputed kings of "pile 'em high, sell 'em cheap" (and of populism in all its shades and colours).
Whilst agreeing that Amazon's attempt to take over the entire book industry from top to bottom has been extremely harmful, if the Net Book Agreement had held, one of it's major advantages, discounting, would have been impossible here.
Discounting is impossible for new hardbacks in Germany -- not for paperbacks. Nor, of course, for used books. And it's via paperbacks, used books, and obviously e-books (Kindle) and audiobooks (Audible) that Amazon makes most of their money. So do most of the other players, for that matter, so it's definitely not Amazon alone -- but they're the most destructive player by far.