Caltech is a very selective school, and I'd bet that the majority of applicants have taken the SAT or ACT. Lots of research has shown that standardized test scores, in addition to high school grades, predict college success better than high school GPA alone. It's strange to throw out relevant data when making an important decision, and that's why I think Caltech and other schools that are doing so are trying smuggle racial preferences (banned by a recent Supreme Court decision) into the admissions process.