Nothing has been proven, the article in question is about how to STYLE the tabs to get the rounded corner design, not how they function as tabs. That is a secondary concern.

The use of jQuery was to provide the functionality so you can see it in action. If I felt the need I could easily recreate the tabs on a series of pages that do not require javascript at all.

The only reason this might need javascript involved is if the tabs are changing content on the page without loading a new page, such as swapping out divs in a container.

I believe you are confused about design versus function.