It creates bad outcomes where students retake classes in the summers as a profession and game the system.

It also puts you at a disadvantage if you come from an immigrant area or poor area where your 90% will not count as highly as someone with 60% from the richest areas with a trackwork of success.

It really punishes anyone not rich and locks them out of elite universities and pushes most of the poor out of average universities.

A single test where everyone can study and pass seems more fair than basing it on things that can be impossible to change like where you grew up