Information hierarchies have a bunch of channels to get the reader to understand what's important and what's not. Text size, color, motion, placement, rotation, contrast, images, etc. all contribute to drawing the eye to key pieces of information.

The link you presented is simple, yes, but the information hierarchy is nearly flat. It presents all the information as equally important by reducing the channels for information transmission it uses.

Our eyes focus on certain details because we have monkey brains that have been trained to pattern match certain things.