Problem is that threads don't mate up on the "peak and valley", nor are they measured in that manner, but rather on the Pitch Diameter (sort of datum line at about the midpoint of the flank). There should be a standard tolerance for the PD for any standard thread and tools to measure this directly. There would always be the old 3 wire method of measuring the PD if the more user friendly tools weren't available. A CNC lathe wouldn't need reprogrammed, just adjust the offset for the threading tool. The operator will be doing that anyway as the tool wears and the bearings heat up and cool down. Been a while since I ran a CNC lathe, but threads aren't that hard on one.