HR departments say so because if no one ever gives interview feedback, no one will ever get sued for giving the "wrong" feedback. They are like the legal depart

HR departments say so because if no one ever gives interview feedback, no one will ever get sued for giving the "wrong" feedback. They are like the legal department in that they will never look to help a company actively gain a competitive advantage, and certainly never to do the decent thing by people outside the company's management.