> All they really want is a program that will challenge their kids and surround them with an equally motivated peer group that has a goal of getting into a selective university.
You have part of that right. What most parents want is a magic piece of paper that says "Good for one admission to Prestigious University." The achievement of their child and whether it brings down other students is irrelevant to them. The credential is everything.
We see this with AP (Advanced Placement) programs. Parents will sue the district to get their child put into the AP class (who almost always also has an ADHD exemption for extra time on all tests due to "anxiety")--who is completely unequipped for the class and then doesn't succeed in the class and scores a 1 on the AP exam afterward. This is practically a tautology because if the parents were actually engaged in their child's education, the child would already be in the AP class by credential.
This, of course, brings down the children who do belong in the AP class. But the parents don't care because now their child is punching above their weight in terms of credential.
This is the standard "Something ceases to be a good metric once it becomes known to be a metric."