Non-creators always offer copious advice to creators on how to create. ;)
Say not “non-creators”.
Lewis, and especially Tolkien, and all really effective mythologists, were and are “sub-creators”. They have created something - it’s not reality, but it’s still something that wouldn’t have existed without their efforts.
Good One! ... Corollary from Dilbert: "I'll file that away with the rest of the marginally useful things that others suggest that I do."