But in how many cases is the "why" more important than the "how"?

People can drive a car, without understanding any of the mechanical and electrical systems of a car. In fact understanding these does essentially nothing for what most people use a car for.

>If you can’t produce a comprehensive answer with confidence and on the whim the second you read the question, you don’t have the sufficient background knowledge.

And then what? Why would this matter at all? You can successfully use a workout schedule without understanding what its strengths and weaknesses are and how they align with your goals.