In a highly competitive environment like Stanford, isn't it more likely that it's to get more time on tests -> better grades -> higher paying job?
If they need all that extra time, the university on the degree might get them some extra money out of the gate, but I have to imagine it will work against them if they are slow and are always asking for extra time to complete projects. That’s not going to get them promoted and they will stagnate. I’ve also never had any job ask me about my grades.