Not only that, but high performers are incentivised to move to worse schools.
It may actually improve mean outcomes, but harm societal outcomes, as the scientific impact of educated individuals may tend to be power law distributed (e.g. the most important breakthroughs come from a small sector of the population with wildly disproportionate impact)
The bottleneck on research is funding. We have a glut of students wanting to go into research who don't because of how competitive the field is. We then have researchers constantly leaving the field for the same reason.
What breakthroughs are coming from high school students?