The purpose is to be "helpful" and the only reason I post on this site is because I know that Moe Norman Golf Swing fans read this site to find useful information. It is not to argue and fight even though often Egos and the need to be right are often all that is found here.
Often I post things that are "themes" - which seem to come in groups in my golf schools. This year there has been so much "sliding" going on which has stemmed from drills that some teach to slide their hips. I wonder where some people get their information about sliding.
I could show you countless hours of students "NOT TURNING" their hips and sliding - because that is what they were taught or what they thought the Moe Norman Swing was all about.
I, like everyone on this site, look for evidence - scientifically and anatomically. But the real test is when you try to teach someone.
This post was only to help clarify that the spine and hip move together due to hip rotation and perspective from the face-on view does not tell the entire story. The back view tells a different story.
Bertholy's "Buckle, Sit, Slide, Bump" I think is great because he was such an innovator at expressing his ideas of the golf swing and movement however, words, as you can see here on this forum - seem to always create as much confusion as they do clarity.