In the digital age, pen and paper still thrive. Our brains are just better with pen and paper. (I think that's why Apple Pen exists)
In this book, it is not a "how" to do Bullet Journal (BoJo). It's why to BoJo.
It does not tell you how to take notes, it give you a starter method and some example for you to build on.
I personally use the Muji Weekly Monthly Planner, but using this, I can also implement the BoJo method to my note taking and journaling method.
In the end, I think having your own style to make a journal is the best, but BoJo is a good place to start if you don't know where to begin.