“Sorry to say, too many applicants have the impressive stats, but present weakly in the rest.”
The issue is not that they present weakly, it’s that too many present strongly. If your assertion were right, the test score averages for the selective colleges would be much lower than they are, probably like 1200-1300, not 1500-1550, because the lower stats kid presents better. These colleges would only have a few, relatively speaking, high stats kids to admit, because many, maybe most, don’t present well. The 25-75 numbers show a different story, they have a many high stats kids that present well.
“Caltech is the only elite school that has gone test blind, at least temporarily during this pandemic.”
Cal Tech is a outlier, probably along with MIT and Harvey Mudd that don’t need SAT/ACTs or subject tests to evaluate a class. They do though expect you to, if the opportunity is there, to take AMC and AIME. These scores differentiate the students that apply. That and rigor, specifically when you took Calculus, what courses you took after Calculus. That gives them, MIT, HM, a pretty good idea on the academics. This also applies to many STEM programs at Stanford, ivies, CMU.