James welcome to LuLa - I see that this is only your third post.
Jeff's book is not limited to a discussion about Lightroom.
It starts with the nature of digital images and the file types and goes from there.
Postprocessing is not just how Lightroom works but also incorporates those occasions when Photoshop would be required for specific tasks.
The idea (Jeff is welcome to contradict me if he wants) is to present an application independent approach to post-processing using the most useful and practical courses of action.
Lightroom does play a starring role but Photoshop also has a more limited, but still Oscar-nominated, cameo role.
Good luck with your studies by the way.