The way I see this, it is easy to argue the point both ways. One reason for this is the steel tapes we use. How accurate are they? Remember Dave Katz sent his tape to NIST prior to his measurement of the London Olympic Marathon? As I remember, his 300' tape was determined by NIST to be short by slightly more than 1 inch.
As Duane points out, this magnitude of difference (temperature corrected) becomes material over the marathon distance. It could manifest itself in the "slower runner breaking the record" phenomenon. I find myself wondering, like Pete, what we are pursuing here. It seems to me we are in effect making consistency in measuring a higher priority than actual accuracy.
Should we all submit our tapes to NIST to determine how much adjustment to make to each tape, hence to each cal course? What should be our "tape accuracy" standard? I am simply wondering how meaningful this new calibration course standard is when tape lengths apparently vary so much.