>>518592754
Flags, unlike the mondern made-up corporate HR state flags of fruitcake states, generally develop somewhat organically. This usually happens through critical junctures, independence wars are a good example. The Confederate States were pretty much engaged in war within a few months of existence once the feds refused any and all diplomacy.
Anyways through the course of the war, you can clearly see a organic gravitation towards the Lee Battle Flag and deviations of it. That's why when the generic placeholder "Stars and Bars" was replaced, the flag included the Lee Battle flag type design in the canton. That's why the final flag "Blood Stained Banner" included it on the Canton. That's why 90% of regimental flags were some derivative of the N. Va. Battle Flag. Don't take my word for it most of the flags had begun gravitating toward that design or some derivative of it particularly HQ flags.
The point is, by wars' end that design had clearly and organically come to represent the struggle (which is what a REAL flag is). And it is not odd that people would take that canton battle flag design and stretch it across the whole rectangular field. In many ways it is a natural evolution of the design.