I don't think PMP certifications are any worse than any other certifications, though often, as with other certifications, they often aren't worth the paper they are printed on. And I agree that the project managers often have little-to-no technical expertise in the project they are managing; but that's not supposed to be their job. Their job is supposed to be to manage the job that the experts are working on and let the experts do their thing. Although they (PMs) should have at least enough knowledge to understand discussions at a high level, facilitate when necessary and recognize when one of the experts is blowing smoke out his/her ass.