Credentials seem to make the most sense when you are just starting out or when you want to start over in a new area because you have little if any experience.

More regulated areas simply require a piece of paper. Not that this always seems to help: in California to be a mortgage broker you need a real estate license which requires you pass several college level classes, take an long exam, get fingerprinted and have a certain amount of experience. Yet none of this prevented all the problems we recently saw.