Who doesn't know a bunch of brandname influentials to contribute gushing testimonials about a newly published book? The whole deal makes about as much sense as submitting three names as references. Of course, unless we are brain-dead about how to read relationships, the three will say appropriate things about us the job candidate.
Yet, testimonials are growing in number. Recently, a colleague told me that her publisher demanded 30 testimonials on Amazon.com. Although I'm a nobody, she still requested mine. We comply.
In addition to increasing in volume, testimonials are invading the inside of the book. No more just on the front and back covers. I had to read a bunch of books on sports to put together a book proposal for a client. Sure enough, about four pages in the beginning of several of the books had testimonials.
Some day, some confident author will demand that his/her network not post testimonials on Amazon. There will also be none of that sort of thing in the book. For the time being, I feel compelled to advise clients that, yes, they do need the testimonials. Not having them could constitute a competitive disadvantage.