The real issue here seems to be about "fairness". Is it fair to the airlines (or Amex) to book a flight that you have no intention of using just to gain access to a lounge? Rules in our society almost always favor the corporation over the individual. It is considered illegal to book "hacker" fares that can save you money but it is completely legal for airlines to overbook and bump passengers off of a flight that someone paid for. Our society is based on loopholes (real or perceived) that some people use because they think it is "fair". That is unlikely to ever change.