Lets ignore your claim at possible discrimination, and ask what the ability to game a high score on an ACT/SAT has anything to do with how successful or contributing to society someone will become?

In the internet age that we live in today, with access to all sorts of methods of memorization, I would argue scores on a standardized test are largely irrelevant, beyond testing for if someone can pass a test or not. The highest score goes not to the person who thinks critically but to the one who gamed the system the most. If you can teach someone to win at candy-crush, you can get them to ace the SAT's.

Some of the most important people in society have not typically done well in structured schooling, and this is in part because a lot of education is bs in the first place.