This is an absurd statement. There are many complex undertakings in sport where even the very best get better with practice and can't tell you why. In fact, the ones who think they can tell you why are the one's to be most skeptical of.
You are just making stuff up or regurgitating material from a pop science book.
Instead of accusing others of making things up, perhaps step back and re-evaluate the conversation you're taking part in. In this instance, it appears that you misunderstood or skipped over the word "learning".
They can't tell you (not everyone is eloquent), but they sure know why. Struggling to put something in word is not the same as not knowing.
Much of human behavior is evolved so that we don't understand why. For example human morality is an evolved trait, but you wouldn't know it.
Please explain walking to me so that I can explain it to a person who forgot how to walk such that he can walk after the explanation.
Nope, they don't.