The guide is more akin to a book than to looking at disparate options and comparing (google results, shopping etc.)

Would you expect someone to read a book by looking at the table of contents, going to a chapter, going back to the TOC, going to the next chapter?

It's not that the site is impossible to use - it's that a fairly basic and fundamental part of the UX is broken, yet the entire thing is a guide about UX. It just makes it harder to believe that they have expertise in the field when they aren't practicing it on their own work.