I picked up this book as I'd been seeing Tailwind alot, and was wondering what the fuss was about. I do remember thinking, wouldn't it be good for a script to run to create a stylesheet of only what classes you're using... and that's basically what the first chapter or so says Tailwind does. So I'm a convert on that basis. Also tailwind has the advantage of not having style logic in stylesheets all over the application.
Does a Tailwind book need to exist? Probably not. The documentation probably covers everything well enough, and after reading the first chapter or so I started a project using tailwind and looked up any classes for the styles I already knew I wanted. So I'm not fluent in tailwind yet, but I know what I want and I can find it quickly enough and it's easy enough to read. I did have a takeaway from the book of finding that you can add "[]" to insert arbitrary css, which is what I do for hexadecimals quite abit.
Since using Tailwind I do have abit of beef with lists and having to apply the same classes to each item on the list. So I probably will end up using abit of a hybrid of tailwind plus a stylesheet on a component for things like that with repeated content to avoid the long list of classes on list elements that aren't in a for loop or mapped to an array.