Any information carries the vibrations of its source. At the same time, the one perceiving the information has a fairly wide range of possible focus on it, depending on the conditions and the principle through which that information is transmitted.
Listening to a story in a crowded, noisy place is not the same as listening to that same story one-on-one, in silence and calm.
That is why the printed version of the book creates the strongest focus of perception: a physical object without unnecessary noise. The printed version of the book is a self-sufficient tool for inner work.
The book exists only as a hardcover in order to create maximum fixation of perception on the tool of access to Truth. It contains pages for personal notes and markings made during the process of working with it, and is intended for repeated, long-term use.