It's a plug for the book the essay is from. It barely introduces the subject. The book might be interesting and explore all of this stuff in depth, but excerpt

It's a plug for the book the essay is from. It barely introduces the subject. The book might be interesting and explore all of this stuff in depth, but excerpting a section like this is poor form. It's on a website so it shouldn't be a space issue. If your going to advertise your book like this, the reader should get something out of it.