Harold;
That was my take on what Frank said in his articles originally until I followed several modlers description of a operating session with a copy of the trackplan in my hand.
I lived in Mobile, Al for awhile, met and knew several operators there that would go over to NO quite a few times a year for sessions on the Delta Lines. One of them even told me the story of once when the NO Police "raided" the RR, because neighbors thought a "gambling den" was functioning in his basement. The officers were quite surprised to find just a bunch of guys "playing with trains", instead of something illegal going on.
Granted he did advocate not adding additional track as a true staging yard he did advocate having enough track to allow for "hiding" trains in areas not easily seen until needed. His "all the world is a stage, and the trains merely actors" concept is what we now know as staging. He used small yards, long sidings, generally hidden by buildings &/or some scenery, to set up the "staging" of getting trains ready to come from the "wings" onto "center stage" do their work, and exit back into the "wings".
The main reason, I believe, he never advocated separate staging areas, is that the Delta Line trackplan as built, would not allow for it. It was O gauge, and for lack of a better term, a real spaghetti bowl of track. He had enough places built in to the plan, those yards, sidings and some spurs, to allow for the type of staging he practiced. He did indeed practice staging, and advocated staging, but without the use of a "dedicated" staging yard.