That probably happens a lot, but there's another mechanism by which it could happen, that requires no malice: the brand gets a quality reputation, which increases demand for its products, and they are unable to produce quality products at the rate needed to satisfy that demand. Then it's easy to reason that it'd be a net benefit for everyone to loosen the quality requirements a tiny bit, in order to satisfy the demand of more customers. People used to the quality will barely notice any difference, and then twice as many people can get that experience.
That works once, but when applied again, and again, and again, and again it becomes a problem, even with zero ill intent.