Traditional journalism jobs may be dwindling, but the Internet offers many new possibilities for writers. It has been a boom in what used to be called vanity publishers, which can efficiently produce physical copies that look just as good as anything from the traditional New York houses. But an even bigger factor is the explosion in electronic publishing. It used to take the same time to produce a book that it does to produce a baby. Now it takes about as long as boiling an egg. In 2006, before Amazon supercharged electronic publishing with the Kindle, 51,237 self-published titles appeared as physical books, according to the data company Bowker. Last year, Bowker estimates that more than 300,000 self-published titles were issued in either print or digital form.

Mr. Rutherford’s insight was that reviews had lost their traditional function. They were no longer there to evaluate the book or even to describe it but simply to vouch for its credibility, the way doctors put their diplomas on examination room walls. A reader hears about a book because an author is promoting it, and then checks it out on Amazon. The reader sees favorable reviews and is reassured that he is not wasting his time. But in essence, they were blurbs, the little puffs on the backs of books in the old days, when all books were physical objects and sold in stores. No one took blurbs very seriously, but books looked naked without them.  Also in theory, at least, good reviews are proof that a writer is finding his or her way, establishing an audience and has something worthwhile to say. 
So if you relied on book reviews to guide you to the latest new writer, be warned, that five star review may just be a review that has been paid for by the author. And who are these reviewers- you would be surprised to learn that Bill Clinton is one of them!

And what of the future? The theory is that in the long term, the (real) bad reviews will then drive out the (fake) good reviews. And then you can really believe the reviews that you read.
But this seems to underestimate the powerful motivations that writers have to rack up good reviews — and the ways they have to manipulate them until a better system comes along.