Discoverability is vitally important. On the other hand discoverability is almost irrelevant. Both of these statements are paradoxically true.

Here are two blog posts, each taking the opposite side. The first one, from Publishing Perspectives of 20 March 2013 about Search Engine Optimization and Discoverability tells you you’ve got to do it. This is of course true: if you don’t get the metadata out there nobody on-line will ever be able to find your book.  But as Joe Wikert points out, at The Average Joe, 27 April 2015, there just aren’t people out there saying “Gee, I wish I could discover more content”. So it’s easy to get trapped into thinking discoverability is going to help sell books. It isn’t: but lack of discoverability will surely prevent sales. You’ve got to write a book people want to read. Getting them to realize they want to read it is of course the secret sauce. Having got their attention, then you need to ensure that the people can actually find your book.

See also Metadata and discoverability and Metadata glossary.