Have you ever been a pro! Arm chair QB! And to your question. That and more! Much more!
U don't need to be a pro to be knowledgable, a handful of the top "gurus" aren't pros and being a pro half of them are a bunch of idiots, Ronnie and flex for example had really good genetics but when it came to diet, and drugs they were dumbasses, they had gurus who basically held their hand on preps, training and posing
Guys like Shawn ray, milos, and Dorian were knowledgable