Delta once said ‘if everyone’s elite, nobody is.’ But if everyone has lounge access, nobody does. To mitigate overcrowding Delta and American Express worked on getting Delta premium card customers access to (also overcrowded) Centurion lounges, and to build Centurion lounges in some Delta terminals.
That hasn’t solved crowding because more people have access, and are trying to use the lounge, than there’s space. That can mean lines to get in – a wait list.