Credentials are worthless if they aren't backed up with knowledge and/or experience.
What kind of idealized dream world do you live in? I have two words that can prove absolutely that credentials alone can have great worth, absolutely lacking any reasonable degree of competence:
Affirmative action.
Personnel departments, nationwide, are now so cowed by lawyers that they'll make that incompetent hire no matter what just to fill a slot, but only as long as the applicant possesses appropriate credentials. Therefore, credentials indeed have worth, any influence of reality notwithstanding.