Also, imo, the vast majority of students did not benefit. It's not like they were all brilliant. They basically passed a standardized test that they spent a few years in prep classes to pass. What this measured was whether your parents were tapped into particular social circles and knew to put you in prep. Once you were in the school, if you wanted good teachers, you had to take honors. I had a fantastic history teacher who talked about how he loved teaching regular history, but he was constantly pressured by administration to only teach AP. So for a lot of students who didn't have the grades to do honors, they got stuck with the mediocre teachers. Not to mention, psychologically, it sucks being in the bottom 50%. There were so many kids who thought they were dumb or underachievers, but were really just in the wrong environment. When they went to college, they blossomed from not being in such a rat race.
I'm not saying the solution is to eliminate gifted programs, but let's not pretend that they're universally great for kids. They're often much more status games than actual educational fulfillment.