It's a field of study that has research to back it up. It's great you find that link legible, but most people would not. Even most developers would find it helpful to tweak whitespace, use headers, and layout the content a little more structured to improve legibility.
Most of the UX studies are subjectivism dressed as objectivism.
The entire field is like nutrition or fitness, 90% of it is bogus and made up. None of these studies have proper controlled experiments while still trying to appear as authoritative.
No one takes a step back and realize that physical books are an interface and so is your kitchen. Photons hitting your eyeballs have no clue if it came from a computer monitor or the world around you. Organizing visual information is far deeper than these "UI/UX" experts.
I'm sorry, you just don't know what you are talking about. This is a widely studied area in human computer interaction both academically and informally.
I don't understand the infatuation with obscure irrelevant studies to make a point. None of these are remotely relevant to the page in question. Linking to sources isn't a way to escape basic common sense scrunity.
Basic common sense says the site has poor visual hierarchy. These links in the past several posts have been to highlight that the common sense understanding is that it has poor visual hierarchy.
The basic scrutiny agrees with me, and the sources are to help provide both subjective and objective reference that shows that, yes, the common person would prefer a more structured layout.
None of those back up your assertions about the linked website, which has very clear information hierarchy. Category nav links at the top. Key topic links in a list and sublists (how's that for hierarchy?). The information hierarchy is easy to see and navigate, much unlike modern websites which mislead the reader with a lot of irrelevant images and layouts.
