The contention is in the definition of the word "know." Jony Ive knows glass in the sense of the way a particular type of glass reflects sunlight, or feels (ie

The contention is in the definition of the word "know." Jony Ive knows glass in the sense of the way a particular type of glass reflects sunlight, or feels (ie: to the extent that it solves a particular problem for him), but he absolutely does not know or care how that piece of glass is manufactured. The difference for a designer between knowing when to use a button and when to use a link does not depend on them knowing <a href=""> vs. <input type="button />. It goes without saying that designers should know how people will interact with their products, but knowing how to code is just one way to do that, and it is not the only one.