Why is there no more longevity with today’s RB’s?

Possibly the new technology that teams use to assess a players performance, stamina, injury prevention, etc has something to do with it. I forgot the name of it, but SP talked about it at great lengths during the Super Bowl. The analytics these days are used in many games and sports. The days of good old fashion players grinding/gutting/with grit is a thing of the past. Not to mention, for instance, a RB by committee is a strategic approach to victories