Who defines a best practice? Do they have some particular authority? What empirical evidence backs it up? What makes it so unequivocally correct in all circum

Who defines a best practice? Do they have some particular authority? What empirical evidence backs it up? What makes it so unequivocally correct in all circumstances? Have you mathematically proven it to be the "best"? Is there a history of other practices that preceded it with explanation as to the superiority? The answer is basically no/none/unknown to all of these.