The main problem I raised with the Gaokao isn't that it's biased, but that it has negative effects on the way education is conducted prior to university.

It's not difficult to find first-hand accounts of this; go browse social media posts by teachers in mainland China if you're curious.

There are similar problems of "teaching to the test" in other contexts, too.

I'm not categorically opposed to standardized testing and I never said I was.