> Those aren't books. They're printed blogs you pay for.
If you are going to make an outlandish claim like this, at least try to post some criteria to defend. Not doing so has led to you not realizing that you can't without also excluding works of classical literature like Sense & Sensibility (which was self-published by Jane Austin).
There's also more direct problems with the arbitary line you are trying to draw, like best-selling book The Martian, which was originally published as a blog, then self-published as an e-book, then officially published as a book by a major publisher.
Every book can be published as a pdf. That doesn't mean that every pdf is a book.