Pretty can be functional, in fact pretty is functional. Pretty is about expression and exploration. Pretty doesn't solve it all alone but neither does function.
Would you critique a blogger because his posts where way too philosophical and reflective rather than utilitarian?
Would you critique a developer for creating experiments in HTML5 that have no utility?
I would agree with him if HP, Amazon, BP and all the other fortune 500 companies where pretty over functional but they are not.
His argument is based on sites who's purpose is to be explorative and expressive not purely functional.
Design is not about style, but style is a tool the designer can use.