Richard Lee in Modern Reloading claimed that he and the late Dean Grennell (for you youngsters, Dean Grennell was "Mr. Reloading" for over 40 years prior to his untimely passing) were able to consistently dip powder charges with Lee dippers to an accuracy level of 0.1 grain.
For liability purposes, I'm sure, Lee includes a dipper in their die sets that is measured at the low end of the powders they recommend for the given cartridge. Larger dippers will give measurements of powder higher on the scale of acceptable loads. Dippers to measure powder do have a place in loading, even today, and with practice, can be very consistent in powder weight dipped.
Rember, our shooting forefathers rarely had a scale to weigh their powder charges, but, depended on a volumetric measure for reloading.