Only 5.3% of US welders are women. After years as a professor, I became one

OK, I'll ask. What's wrong with using a tape measure the way the guy suggested to measure a length of pipe?

Best guess is the tolerance required for the pipe length was tighter than you can reliably get going off of a tape measure foot (which are often loose, worn, bent, etc. and not a reliable starting/zero point for precision measurement).