[brightlancer]

> You can improve the outcomes of the non-low-performers, but it's hard to say it's a "net societal improvement" because the low performers are also part of society.

That depends on the improvement vs loss -- IME, it is a net improvement.

With 100 students, 5 are disruptive, verbally abusive, maybe physically violent. How much does that 5% bring down the other 95%? If we remove that 5% from the other 95%, how much does the 5% lose versus the 95% gain?

IME, the gains in the 95% are miles ahead of the losses in the 5%, which makes it's net improvement.