I think the difference is that the author defines "designer" as someone who excels in some "designer-like" quadrant of the intelligences. Which is a load of self-entitled bs.

A designer is someone who designs—it's defined by action, not beliefs about competency. If you design things implemented in HTML/CSS and you don't have any proficiency at all in those technologies then you're very liable to be a worse designer than someone who does. The argument of how often that is true is what's important here and it's never actually discussed in the article.