I generally agree with the article's premise and conclusions, but the lead in is not true:

> They make more money from mileage programs than from flying planes—and it shows.

Delta reported 5% of its revenue came from its loyalty programs in 2022 (2.5B of 50B according to 2022 10k). Although in the June annual shareholder meeting, it expected >6.5B in AMEX remunerations in 2023 with a long term goal of 10B.

American Airlines may have been closer to 10% (4.5B of 49B according to 2022 10k). I can't quickly find any public data on it's long term goals.

Both still well short of "more money" than from flying planes.