Judging by your hostility and focus I think my point (which I don't think is trivial to those working with the web) wasn't clearly communicated.
The best of modern web designers embody that philosophical approach in regards to the 'building / making' element of how a final web design lives. This is a fuller consideration of how the design works, and can only be achieved by working with the 'materials', just as Ive mentions is essential at Apple for product design.
I never said design can't or shouldn't use napkins, keynote, Photoshop, Illustrator or whatever a designer chooses, or pass any commentary on how designers at Apple internally prototype UIs.
I did imply though that a web designer that stops at the PSD mockup stage doesn't embody the design approach Ive is discussing in the article. Without working directly with the materials (HTML / CSS) you are deciding not to entirely consider all elements of how the design lives:
* are webfonts available for this typeface?
* does CSS provide those visual effects, and if not, what fallback designs should I consider?
* can the design work across all target devices / browsers?
* will the page weight be too large to support this particular design approach. Can I simplify to avoid this?
Mocking up a variety of screens in Photoshop does not cut it at the best end of the scale as a web designer.