It was invented to prevent people from thinking. Take the Greeks for example, when people with high IQ had enough time to think, they came up with important “stuff”. In our days the lords in the higher positions of the social hierarchy don't want people to think, so they keep people busy with bullshit jobs that are not necessary in the first place. Or keep them at least 8 hours (plus commuting hours) doing a job that can be done in 15 minutes from home. The important thing is not giving them time to think for themselves.