That is an equity issue. Those students who are disadvantaged at the start are often disadvantaged in several ways. And it perpetuates itself: those lower score

That is an equity issue. Those students who are disadvantaged at the start are often disadvantaged in several ways. And it perpetuates itself: those lower scores will be used to hold the same students back or otherwise decelerate learning, leaving them once again starting off disadvantaged the next term. It also shapes their perception of their ability to advance, and importantly it shapes that perception for their educators and their parents/guardians.