"Grimoires assume that the reader already has a practical knowledge of how to work Magick. This is why it's quite useless to pick up a grimoire and attempt to replicate what it says."
It's like Pinterest and knitting. People who knit cruise Pinterest for examples , illustrations, and ideas for what to knit next. "Knitters" can look at a couple of pictures of a finished project and can analyze what they see to make their own. A person who didn't already know how to knit would find the task impossible.
While I understand this, at the same time, I've never found a grimoire useful. Maybe it's because I prefer to work from basic principles and because I loathe reading rituals. (Once you've read so many, there's not much left to learn there.)