The idea being, say you want a 7 degree G440 Max driver. The lowest loft that comes in is 9 degrees. The sleeve is adjustable +- 1.5. But, because of manufacturing tolerances, some of the 9 degree drivers are actually more like 8.2 degrees, or 9.7 degrees. When you buy it, you don’t know what it actually will be.
Digital lofting allows you to tell ping “I want a head that is closer to 8-8.5 degrees (as opposed to potentially being 9 on the dot or closer to 9.5),” so that you can turn it down to that 7 degree setting you want. Ping will measure their 9 degree heads, until they find one in your range.