I had the same issue as the last poster. I fly WN primarily- as Alist Pref free drinks etc. I signed up for an alternative airline but frankly am not sure if it was United or American Since I often fly FC the credit was a non issue.

I don't disagree there are some benes there but they are not 'universal' and
require some 'effort'.
A case in point for me is the Priority Pass. When originally offered by Amex it only covered one person which is of limited value since I would use it primarily with my wife. It also required some 'runaround' to apply for. When I got CSR it included guests and I checked a box online and cards were sent a few days later.
Likewise Centurion Clubs are great-they are just not in airports I frequent. In five years I used the 1X in Vegas (this wasn't convenient to the airline I was flying) and I used the Delta Club benefit once.
AA clubs of the past were a much better prop. So while a Delta flying cardmember might have great affinity for the Plat it doesn't offer me much in these areas.

At the end of the day I am just expressing my feelings after holding the Plat Corp for 15 years and Gold for 40. I am extremely pleased to have found the CSR (with 100,000 sign up) and have suggested it to colleagues with great feedback from them.