The low 000s are all generally pretty meta subjects, how we interact with and organize knowledge in general. Journalism and library science deal with reporting and classifying information, computers and programming deal with processing generic data, unexplained phenomena deals with things that can’t be assigned to a specific subject by their very nature.
Witchcraft, Feng Shui, and Tarot are all generally found in 133 (Parapsychology and Occultism), although I could imagine particularly high-level books to be sorted into 003 (Systems), since they are supposed to be comprehensive systems.
Books about computer hardware would be next to electronics. Computer science is where it is because it’s a more abstract topic about general information processing. If anything, I’d argue that fundamental mathematics belongs in the 000s with it.







The theory I’ve read is that lots of people are into a bit of the taboo/forbidden partner aspect of an attraction they have toward a real person in their life: their neighbor, platonic friend, co-worker, etc. But most of these connections don’t really feel all that taboo when it’s someone else, so the “step-” angle is just a generic stand in that carries the forbidden aspect without going too far.