Ball gets set on the field for a new series, and is not on a five yard stripe, might not even be on a yard line. Chains are set, which is certainly an inexact "science". Offense moves the ball approximately 10 yards, and official spots the forward progress of the ball, which may have crossed a sideline, may have been in a pileup, etc. Again, an inexact "science" at best. If either of those spots is within a few inches of "reality", great.
And then when make a big production of bringing out the chains, getting the clip set, stretching the chains, checking the ball against the pole, all for something that was set up by a couple of best guesses to begin with! THIS is the point when we try to get precise?
It's a freaking coin flip anyway! Let the R look, flip his mental coin, and move on. If I never see another measurement again it will be just fine.