It's unfortunate that the label 'music theory' has become associated with this basic stuff Only in the way that the label mathematics has become associated wit

It's unfortunate that the label 'music theory' has become associated with this basic stuff Only in the way that the label mathematics has become associated with arithmetic. The stuff here is what you need to know in order to get started analyzing music of the common practice period (you'd need set theory to talk about the pitch content of most music after 1900). But when people get doctorates in music theory, they are not stil studying the circle of fifths. They use these concepts to describe music in order to come to some understanding of how and why it is structured.