Buying a used aircraft with payments isn't the premise.
It's also an factor that cannot be summarily dismissed, as you appear to be doing.
If that theory was accurate in the long-haul sector, in general we would be seeing airlines shy away from new aircraft, keep what they have until the wings fall off (no payments)
We DO see that.
Airlines like UA, BA, CX, TG, etc are all still flying 777s that are 23yrs old, with no immediate intention of retiring them.
AF, LH, SN, JL, NH, KE, OZ, etc are all flying longhaul widebodies age 20 and older, with again no immediate retirement at hand.
Heck, DL's oldest 77E is only 18, and some are a half-decade younger.
and tend to look for used aircraft that have lost most of their value for fleet replacement/expansion.
Yet again, you're adding something that doesn't exist by the airline in question; and attempting to pass it off as a parallel.
Once you add acquisition cost of ANY kind to the equation, the economics significantly change.
As to why you have difficulty grasping it, after multiple people have brought it to your attention, I'm at a loss. But repeating it doesn't change the incongruity between the theoretical you're proposing, and the actual practice that DL and others are operating.
Clearly, that's not what we generally see in the industry.
*buzz* Wrong. See above.
I myself, suspect a more prosaic motive... ~Thranduil