All I am saying is that the policy won't thin the crowd given Delta Reserve holders will join us pretty soon, especially at LAS and CLT where there are no sky clubs.

If Amex really cares about reducing crowd, there could be a reservation system with confirmed ticket information. The other way is to limit the time in the lounge and have a credit card "swipe in and swipe out" system (1st hour is free, 2nd hour charged $20, third hour is another $20 etc)