The author urges readers to discard their beloved laptops loaded with tricky Office software and start using pencils and napkins. Think how many people are going to follow such advice? It is like asking them to move out of their spacious apartments back into wild nature. Sounds crazy enough to write a book about it , but nobody will do it in real life.
In my opinion, creating presentations and diagrams needs to be assisted by software. Of course, modern day software is not perfect, but this is just matter of time.