I wouldn't be surprised if part of the reasoning is there was a threat to power that would come from an overskilled person taking a position. For example, that

I wouldn't be surprised if part of the reasoning is there was a threat to power that would come from an overskilled person taking a position. For example, that overskilled person may not fall for certain lies or controlling aspects that the manager uses on actually-unskilled labor, who presumably don't have industry experience or are too afraid of losing their job to cause a fuss.