I totally agree, and I have never claimed Delano's photos will provide anything near precise color matches of individual colors.
And having spent part of my career analyzing human vision in effort to improve military night pilotage systems (how do you integrate sensors and display systems that allow a helicopter pilot to fly within the trees at night by trying to recreate an image that has some semblance to what he would see during the day), I am keenly aware that the human eye works nothing like a camera and is an awful colorimeter - almost useless. It only becomes somewhat useful when the spectrum of the light source, its intensity, AND the variety of colors in the person's field of view, are strictly controlled. That is certainly not the situation in a model railroad.
Combine that with the variance in human color vision and I am not concerned with precise color matching - at all.
It gets back to artistry - I would like, someday, to create a scene that resembles the Delano photos - a vast yard of sooty and very muted rolling stock, but interspersed within it, a few freshly painted colored freight cars, in some cases with vivid colors, jumping out at the viewer.
I would much rather recreate that scene (for WWII), then try to precisely match the color of even one freight car.
People have the perception that the eras prior to color film must have been boring from a color standpoint, yet that is not at all the case - and personally, I think it would be fun, artistically, to drive that point home.
Hence why the Delano photos remain my gold standard - for the impressions they convey, which I am 100% sure are correct, not because I want to use them to match colors.