Okay update, only one source so far (and skimmed a second) but both seem reputable. Rationing has been done in the past, but it sounds like that because the US joined WW1 late, it didn’t reach the point where rationing was a legal requirement. There was propaganda saying use x instead of y (ex. use syrup instead of sugar) and don’t overeat but there were not firm laws in place requiring you to listen (unlike what you see in WW2 for example). I don’t know the sweetener used in Oreos now or then, so they probably did fine (not sure when their popularity peaked, if it was from the start or later on). So yeah, sounds like their debut date wasn’t too unlucky, if it happened right before WW2 I wouldn’t be surprised if it made business tank soon after creation.