Earlier quoted context omitted.
I think there's no doubt that it's a good thing for the students that go to these schools. The question is whether it's good for society as other schools may suffer
How other schools will suffer? Endowments from rich parents? Being rich does not mean your kid is smart and these gifted schools should be very selective to whom they admit.
But it does mean you can pay to get them tutored to jump through hoops, and generally push them harder. There's a very strong relationship between wealth and elite college admission for example. Which is down to culture and opportunity as much as gifts and talents.
If being selective means controlling for socioeconomic background when assessing potential - then I'd be more of a cheerleader for it.