There is even more research on that low IQ people actually cost production.

Like, that one person who is not quite computer savvy, who puts the database in the trash folder, and presses delete forever, when she was asked to delete some records. Causing the smart people in the company to have to work hard to bring the database back, and get it up to date again.

Unlike the military, we, the society, have to deal with ALL of the people.

Unless we are going to start shooting or euthenizing people. Which usually doesn't go well.