Maybe you can’t have both? I don’t know, but that sounds possible?

An example is putting stupid kids with smart kids in the same class. The stupid kids probably benefit but the smart kids are probably hurt.

The US not only separates smart kids into different classes, eg AP and IB programs and early admission to community colleges, they separate the elites into whole other schools, eg private boarding schools, magnet schools, and technical schools.

This is ignoring the huge baseline variance in quality, due to funding and cultural variations.