The short answer is that to leave this in, certainly as written, would suggest that hinge action was tied directly to hit vs swing, that it defined them. You can still swing with angled hinge, or hit with horizontal, so these statements are too limiting. That said, they are reasonable suggestions that explain pretty clearly 'compatible' components.
"Compatible Components", ultimately that's what it's all about; and the 10-19-0 in the 5th edition really shines some light--thanks Annikan. I hold optimizing component compatibility as the ultimate skill. The three imperatives plus the three essentials with the set of compatible components that best suite the individual player. Now we're talkin golf.