I would argue it is impossible to be good at testing and nothing else. Even with a relatively poorly-designed test, there are valuable skills needed to be "good at it". and the current standardized tests have years of development and constant updating behind them.
But if it's a pattern you see from STEM majors from a US school, you could complain to their dean. They usually have industry advisory boards also to get feedback about how students are performing and what is needed.
I am quite familiar now with the SAT, and have taken the GRE and GMAT myself, and don't understand why any of these standardized tests are considered unfair to certain groups. I think they are a good measure of cognitive ability for advanced studies. People are shooting the messenger.
It can be true that the SAT is a good predictor of university grades, and also that there is more to university life, and life in general, than grades. The parent comment is suggesting that optimizing for grades may not produce the ideal set of university students/graduates. But if you think that graduating with high grades is the whole point of the endeavour then obviously you'll disagree.
Certainly I enjoyed spending my time at university surrounded by people who had more going on than just academic excellence.