That is an unhappy medium, but consider what people already do; I'm interested in philosophy and electronic engineering. I know that for any given book on those

That is an unhappy medium, but consider what people already do; I'm interested in philosophy and electronic engineering. I know that for any given book on those topics I want to read, Amazon is more likely than not to just not have them, or only have them with a ridiculous price for second-hand. I don't know if it's the same for fiction readers, but I'd wager that a good proportion of the books fiction readers want to buy (books which they discover by other forms of advertising, Goodreads, word of mouth, Twitter, Reddit, etc.) are not on Amazon either. If what I suppose is true, then the only people impacted are those who find books to read only by browsing Amazon - that is, they use Amazon to discover, not to seek.