cristianl
Good interface designers should definitely know the basics of the technologies used to implement their creations, in the same way industrial designers are expected to have some understanding of materials and manufacturing processes. It's often said that designers thrive on constraints: a designer does his best work when he knows the limitations of his tools, and works with their limitations and defects to create something useful instead of pursuing some impossible level of perfection. Designers, too, have to ship, and they ship best when they know what's behind the facade.
The comments on You're Killing Me, Zappos (http://news.ycombinator.com/item?id=812729) could be boiled down to "You can design a shiny mockup, but you can't make a successful, money-making website."