Yeah, exactly this.
Every job tells you exactly what sort of worker you need, offices favour high education, industry wants low/no education. For every citizen you educate, you're taking a potential worker from industry.
When they're saying theres no workers, they mean 'suitable workers', if every person is a genius and they need mindless drones, they're screwed.
What i find works best is to often create an industrial area and an area for residential & commercial where they're not given access to schooling. By creating them at the same time, what tends to happen is the 'job for life (unless workplace is destroyed)' means that the person moves into the area and theres new work nearby in need of uneducated people.
If you build a huge industrial area and no new homes, you'll end up pulling people from existing homes across the map, and they'll have to travel that distance to get to work - more traffic.