I'm wondering about the motivation to build a Centurion lounge in places where most of the users would be equally able to use a DL SC with their AmEx card. Has AmEx decided that it's cheaper to operate their own airport lounge than pay DL lounge access fees? If the Centurion lounge is equally convenient but better, this would incentivize AmEx customers to pick the Centurion lounge.

Previously, it seemed like the Centurion lounge location strategy was to place them in major airports to cover AmEx customers who wouldn't otherwise be eligible to enter an airport lounge based on their AmEx relationship.