Being certified through the Global Foodservice Institute proves that the individual was able to pass a comprehensive examination on the subject, based upon their academic background and/or experience.  They should provide a benefit to their employer as a result of the preparation which resulted in their certification.

It further indicates their desire to advance their careers.  They have taken the time, effort and expense of seeking new information.

There is no substitute for experience, and for jobs which require experience in the key concepts of that particular job, that should be another component in the hiring or promotion decision.  In other words, we wouldn't suggest making someone just out of college who holds our certifications the F&B Director of the Olympic venue.  But they have demonstrated the ability to learn and retain information, and thus would logically make a good assistant.