If you bought a book on advanced mathematics would you complain that basic principles such as addition, subtraction, multiplication and division weren't covered? Of course not! The author of such a book would consider these topics so elementary and self evident that he/she wouldn't even think to mention them.I am not saying But if you paid your hard earned cash, and bought a book, you want the book to be rich, through, detailed and complete - not half written, and dwindle into notes with information which is everywhere.
The Book of Thoth isn't a beginners text. Like most Crowley books, the reader is assumed to already have some background knowledge. Crowley wrote in the full expectation that his readers were intelligent and motivated people who would make an effort and consult other sources if their knowledge was insufficient. This stands in stark contrast to many modern day books where sales figures are all important. Consequently an author is required to aim for the lowest common denominator and assume that their readers are totally ignorant of the subject under discussion and are in need of plenty of hand holding. This is why there are literally masses of beginner books, but very few for the more experienced reader.