The compare game is necessary. Maybe not to the level of x to y but there is no way to predict without comparing, even if it’s established 40 Times etc.
A big factor to me is pedigree, especially in RBs. Gore, AP, Fournette etc all set the bar on their life running the ball. Every predictor is based on comparison of something.
Comparing players helps streamline thought. Familiar examples rather than dissertations. But before a comparison is made, better know what your talking about. AP compared to Dickerson might work but comparing Reggie Bush to Lagarrette Blount best have counter points.