I love how The Rock is into bodybuilding. It makes sense - he lives it. I honestly think that he was reading Muscular Development magazine, and that is how he got in touch with George Farah. It makes sense - if you want to be good at bodybuilding, you go to the best bodybuilders or bodybuilding coaches, right? Stan Efferding told me that is why he sought out the tutelage of Flex Wheeler for bodybuilding [and Mark Bell for powerlifting].
That said, I do think that a degree of bodybuilding coaching is based on advertising, rather than knowledge.