'Forms' and 'shapes' are just the visual simplification of anatomy. The Asaro Head is a great example of this. Anatomy is like the hard science behind why the shapes and forms are the way they are.
Yeah, what the 4chan discussion is trying to get at is that it is very easy to get caught up in anatomy (as in, "this muscle insertion goes here") while forgetting how these discrete parts combine into a greater whole - which itself can be simplified/stylized. A common example would be the case of naive pencil drawings…