Or, said another way, vocabulary provides us with the words (semantics). You also need a grammar (syntax), which itself needs to be ordered toward an end (pragmatics).

This isn't really what I said, and is considerably less clear. What I meant is that you can't boil design down to certain stylistic flourishes and words denoting them (e.g. "vertical rhythm", to take an example from the linked page). Whatever you're doing, it involves understanding how the viewer will react to what you will show them and why.