If you view the week 1 recording you’ll get a more detailed background and also quite a story. It even gets better and better, week after week, as he goes through the logic and history of their editorial decisions, as well as dramatically narrating the book while elaborating to parents about how to work with their children (in separate sections targeted for them).
Joseph has been a student of Dharma for over 50 years, a meditation teacher too, and has done a three year retreat way back when. As a former educator, I appreciate how he is integrating one genre with another and doesn’t speak down to children, as many folks who write these books tend to do.