Tests have their own sets of problems too. A single, high stakes, high pressure test to determine everything is just as absurd as grades, and tends to bias for those who have time and money to prep.
I prefer wholistic evaluations. You are more than both your test scores and your grades and your school and your demographics. But if you put them all together one can get a decent picture.
You assert without evidence that testing is unbiased. This is widely disputed. You will find some literature taking the opposite view, of course, but given that the debate rages among professional researchers, a plain assertion doesnt carry all that much weight.
Cheating on college entrance exams is rampant in China and other countries. This is another downside of high stakes exams.
As far as a wholistic view, I think including attributes such as grit, leadership, and talent across many areas such as writing, the various arts and many other fields is useful.
I prefer wholistic evaluations. You are more than both your test scores and your grades and your school and your demographics. But if you put them all together one can get a decent picture.