It's possible they wanted that control to open up for max volume on distant station's, or alternately it may have been a simple design flaw in the controls operation. In general people were a lot more able to overlook the little technical imperfections back in the early days of radio. Obviously it took a fair amount of talent to navigate those early radio's.
I looked over the pictures in your link - a very nice job on your restoration. I can really appreciate all the time and effort that went into that set.
