I just realized the really significant thing about the new Supergirl show.
Superman has Metropolis
Hal Jordan has/had Coast City.
Green Arrow has Star City, mysteriously changed to Starling City for the show.
The Flash has Central City.
Batman has Gotham City.
It has always been the tradition to give major DC heroes their own city to protect.
The exception is Wonder Woman. Themyscira is not remotely the same thing. Diana has never had her own city to protect, watch over, and love. (Now, true, so have a bunch of other male heroes - J’onn J’onzz comes to mind).
So, enter the Supergirl show. In order to keep Superman firmly off screen, they couldn’t put Supergirl in Metropolis.
They put her in National City, which is invented for the show.
I am absolutely sure and certain the creative argument was what I said - to detach her from Superman and explain his absence.
But, what this actually means is:
For the first time ever a female DC superhero has her own city.