In what universe is having a dumb, sickly population the most rational move for having a productive nation? Seems like the individual wants and collective wants

In what universe is having a dumb, sickly population the most rational move for having a productive nation? Seems like the individual wants and collective wants align here. You also did not ask for what genes are the most survival of the fittest / evolution of a nation, so, I did not respond with such an answer. Nothing was "changed" here.