I’m not sure how percentiles don’t matter as it puts the scores into perspective?
Just like adcoms know a 34-36 is 99th percentile for the ACT, they also know that 800 on Math II is fairly common and only 78th percentile with 10s of thousand of testers getting the maximum score each and every year.
Adcoms get paid to know what each test score range means relative to other applicants scores which is another way of saying “percentile”.
There is a fallacy on CC that anything in the 700s is acceptable but admissions to highly selective college IS a competition among your high star peers taking similar classes and standardized tests like subject tests.
50th percentile or below scores do have meaning and will not help your cause to the most selective colleges.