I think there is an important difference between a book and a collection of blog posts. Typically a blog post starts off with some general information (because you can't be sure how much your reader knows) and then only progresses so far (because you can't make it too long).

A book is different. The first chapter gets all the general stuff out of the way, then the rest of the book can build on that, without having to recap that information every single time. And then each chapter can build on earlier chapters, knowing that the reader has already met certain concepts. And, within reason, your book can be as long as you need it to be.

There is nothing wrong with creating a book out of a collection of related blog posts. But you need to do a bit more than just putting each post into its own chapter. You need to restructure it, remove repetition, bring related concepts together, and maybe add more information to take advantage of the longer format of a book.

If you don't, you aren't really giving your readers what they expect. And, as an author, you are missing out on the full joy of writing a book.