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
The question is whether it's good for society as other schools may suffer
In a meritocratic society, the smartest kids go to the best schools, then to the best colleges, then the most elite companies, then likely marry someone from school or work, and then have the smartest kids.
Socioeconomic classes become set due the stability of cognitive function across generations.
Is it ideal to have a cognitively and economically stratified america with a cognitive elite and cognitive under-class?
Is it ideal that this cognitive elite has little to no interaction with the rest of America, and little understanding of how the rest of the country lives?
Being smart is not a guarantee of success so we should make it harder so the less intelligent do not suffer any disadvantage.
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.
So...affirmative action like in colleges but for earlier forms of education?
To be fair, the TAG Magnet did have race-based quotas until very recently. Let's just say that the school is now ... less diverse. Although, the 1% "other", which encompassed all East and West Asian, has now makes up roughly one-third of the enrollment. The former court ordered 33/33/33/1 resulted in rejecting some of the most meritorious students.
Given the strong correlation between academic aptitude and economic success, removing the smart students also remove the wealthy students. The funding model falls apart, and the students who remain get even less extracurricular enrichment.
Granted, we could design programs that mostly avoid the problem. In my county, the gifted high school (Thomas Jefferson High School for Science and Technology) only takes absolutely brilliant students. Many of whom truly fit the "too smart to fit in" stereotype. Across a large county, that still leaves plenty of gifted/wealthy students in the normal schools, which offer a broad selection of AP/IB/dual-enrollment options.