Many schools started going test optional a few years ago because they felt a 3 hour exam on a Saturday morning should not define you as a student. During and after 2020, many schools went away from using them because students couldn't take them. Now, schools are beginning to use them again because they're the great equalizer.
Because grades can vary from school district to school district, let alone state to state, you can't rely on them alone. For better or worse, the SAT/ACT is the same exam everywhere you take them. So, while they may not require them, they use them to determine scholarships.
Personally, I hate them. My niece got rejected from top schools a few years back because she isn't a great standardized test taker. She finished 4th out of 600 students in her HS class, and she had a 104 weighted average. But she struggled with a 1290 on her SAT.
I'm torn. I'm very good at standardized tests. Even when I don't know a question, I have a knack for knowing which answer is right. Not sure how to explain it really. Kind of like I'm thinking about what they're wanting you to know and that means this answer (English) or as a math major just knowing what numbers/fractions tend to appear in certain calculations more often.
However, I agree that a 3 hour exam on Saturday morning shouldn't define you as a student.