It's a testament to good structure that the site is legible without its styling.

... legible, not good. If I had to read documentation that looked like that all day I'd consider a career change (or, perhaps, building an infrastructure to improve the legibility of web pages...).

Yeah, props to them for having some structure! It's like CSS Naked Day [0] in the dead of January

[0] https://css-naked-day.github.io/