In 2008 javascript programmers were called "script kiddies" and the language was only starting to get wider adoption. Unless you were already an experienced web programmer back then this was advanced material for most web programmers who only used to use javascript for displaying alerts and cute dynamic features.

Speaking from my own experience, I didn't know about all these prototypes and important concepts for a long time and and did fine. I built tons of web apps without knowing these "advanced" features. It was only when I decided to learn the language seriously that I got acquainted with a lot of these features like the prototype concept, object constructors, etc.

If you can build pretty advanced production websites without knowing these features I would say these features are advanced. That said, it's a different story now because javascript is an important language. But my point is in 2008 it wasn't.

Also this guy created jQuery, if he says it's advanced, it probably was.