Job descriptions are merely guidelines on what an organization is looking for, but they merely state qualifications...not competencies.
Like Mikey, I come from a steel industry background. Our operators needed a high school diploma - that's a qualification. Whether or not they were good operators, this was determined by the process outputs - as long as any nonconformances or defects were within our statistically determined range, they were competent. Those who were not competent required some special attention - sometimes training, sometimes moved to a new position, sometimes shown the door.
Now I'm in healthcare. We have RNs, RPNs, PSWs, HSWs, DWS, and Therapists galore. In the clinical training room beside me, they've been doing IV restart training for the past couple of days. The nurses are all qualified RNs or RPNs, therefore qualified. However, many haven't done an IV restart in years (or only on dummies in school), therefore their competency is lacking...hence the current round of training going on.
Let's look at ISO 9001 certification. How many of us know of a company that has that lovely piece of paper up on the wall, but we all know their system is...to be polite...lacking? They've met the requirements of the standard, but their rates are horrible, their processes inconsistent or unreliable?
As far as I'm concerned, hire whomever you want for a job. Some jobs may require specific qualifications. This qualification, however, by no stretch of the imagination, says that the individual is competent.