This is a school of thought I do not understand at all. Why is HTML, CSS, and JavaScript (+jQuery) considered "design", but PHP/MySQL is considered "programming"? JavaScript is a programming language, HTML and CSS merely a presentation layer (though with quite complicated semantics, hardly intelligible to a non-programmer).
My take on this: if you like web design, learn the fundamentals of both graphic/visual design and interaction design. If you want to program, learn algorithms and data structures. The specific tools of implementation (sometimes common to both fields) are something you can learn along the way, but the fundamentals of each field are vastly different.
Nobody hires an accountant because they know MS Excel. They hire them because they know accounting.