I think they really do want the employees to feel miserable. All the exaggerated criticism from the manager, all the humiliation and underpaid work, it serves them to make us feel like we don't deserve anything more.
My colleague thought for a long time that she could not find a better job because the manager always found a way to criticize her and exaggerate even her smallest mistakes. After she finally left, she got a promotion at the new company in record time.