I confess that I hate this meme. Speaking as someone who has written a fair number of books, I can tell you that a) authors don't always know what they mean; b) even when we think we do, the book is often doing something else that we don't notice until readers point it out for us later; and c) once a book is out in the world, readers' understanding of it matters more than whatever I might think I meant at the time.
This is a thoroughly stupid and reductive meme. It's fundamentally hostile to what literature is all about.
There. I feel better.