Obviously, the fit calculations are based on studies and averages, but I wonder if age is factored in. I am not nearly as flexible now as I was 50 years ago and riding on the drops is more uncomfortable every year.
That said, after buying my new bike a few years ago, I rode with an allen wrench for a while and did some minor tweaks. I think that there is an acceptable range of "fit" and not one precise measurement or location.