This is no different to use of grids and rhythm in web design. These are not arbitrary pseudo-scientific rules imposed by snobbish architects and designers. They're rules of thumb that have been developed over centuries, because they work. It's helpful to have terms of art to describe them. You can certainly break them, but to do that you should know them, and know why you're breaking them. That's why he's said these same rules don't apply to modernist or post-modernist architecture. The examples here are trying to copy a style without understanding what makes the style. They're taking superficial "Georgian" (etc) details and randomly slapping them together. That's why they look so ugly.