I agree. If you want to learn to be a musician, you should start with practice instead of theory. The same goes for learning a language. It's better to learn a few phrases and sentences before the teacher sits you down and starts diagramming the nouns, verbs, prepositions, and so forth.

But just because this course exists doesn't mean you have to go through it first. Go and learn your instrument. Then come back in a couple years when you want to round out your understanding.