actually, i think the author does understand this and in the case of stackoverflow, i think he's obliquely making the case that many of the effects could otherwise be achieved with css without creating the performance and memory hits you might get from using $().

in most cases, js performance is a non issue, but when it is, it's interesting to see how and where you can optimize, which is really what his add-on (again, obliquely the real point of the post) seems to target.

Some what ridiculous that we must figure out what the point of his post is instead of him just telling us.