That is a question for people that study art and not a valid comparison. Studying the occult is different. For example, if someone wanted to learn about the Phoenician alphabet, a book that explains Egyptian hieroglyphs incorrectly would not be a good place to start. It might be good for someone who is well studied and understands how the hieroglyphs turned into other alphabets, but most people have not studied the occult enough to understand Weyer's works were a product of their time and riddled with inaccuracies. Which is why many people still study them as though they were an actual reflection of the supernatural.