HN has a coherent layout, nice spacing, a sensical grouping of content and functionality per component and view or page. stallman.org is a pile of unstyled textual content which was clearly assembled without actually being designed. Regardless of the validity of his site as an example of what he thinks everybody else on the internet needs to do, the two examples are not not in the same ballpark for readability. Between the two, the ratio of structural elements to textual elements isn't even close.

"makes it not readable" would be a weird contradiction.

"doesn't make it readable" is not weird at all.