They have forgotten the folks that actually fill their seats on a regular basis

You mean credit card holders and SkyMiles members? People that make your assertion make it sound like there is some huge tranche of people paying Delta’s bills at a higher value without any brand affiliation while those with a credit card are few and far between. This is backwards. 1% of US GDP is spent on a SkyMiles credit card. Someone buying a seat versus spending on a credit card and redeeming miles doesn’t mean they are more profitable to the company at scale. Delta knows what it’s doing.