Why GMPs? What are GMPs and Why Do We Need Them?

Good manufacturing practices (GMPs) are manufacturing guidelines for ensuring the safety and efficacy of drug products and medical devices. The GMPs are legal regulations, based on the United States Food, Drug and Cosmetic Act. But, why do we need the GMPs? Shouldn't we, as knowledgeable individuals, groups, and companies, be able to figure out how to produce drugs and devices that are safe and effective?