Expecting young people to spend more and more time in education is also a statistical trick. You're not unemployed if you're in school. The incentive was there

Expecting young people to spend more and more time in education is also a statistical trick. You're not unemployed if you're in school. The incentive was there during the 20th century when population growth rates had not yet caught up to the deindustrialization trend. I think population growth slowdown will reverse this credentialism, because we will need more labor and won't be able to tie it up in schooling for years.