No, I think you actually prove the point. The point is that blind loyalty makes no sense at this point. Your loyalty is based on something eminently reasonable - convenience and timing. Paying more for a nonstop is not unreasonable to me, particularly if I need to be somewhere immediately or I just want to get home and stop traveling. Flying DL in situations where a nonstop is not possible or there are better alternatives would be the irrational decision.

I fly the same way. Convenience and timing often matter to me. I am flying to DTW tomorrow for the Lions game on monday night. I had four choices - SW, F9, DL, and UA. For whatever reason SW is always stupid expensive out of DEN and F9 has challenges with timeliness. The scheduling sucks as well for both airlines. That left UA and DL. DL was the cheapest with the mostly reasonable schedule. Pricing and schedule were the drivers and I ended up on a 5:45 AM flight that lands at 10:30. There was a later flight with much better times, but it was $1,000 more, A nonstop is preferable given the west to east travel and potential for delays preventing me from getting to the game. I randomly got the upgrade as well on the outbound and return. Had I picked UA I know for a fact that flying out on a monday morning there was zero chance of getting an upgrade. That did not factor into the decision however. The cost of UA was much higher than DL with almost no available flights.

The question is around the value of diamond. I think it is fine if it happens organically, but flying DL to the exclusion of all others makes zero sense today. Very soon we will be down to a free bag and zone 3 boarding behind the C+ and F passengers. In no uncertain terms do I see an improvement in the treatment of any status level. If one wishes DL to treat them better, they need to pay up and buy the class of service they seek. If I have to do that, there is no reason to avoid other airlines.