1. increasing work hours is a one-time “boost”. It gives a numbers bump once. It’s not continued growth.
2. working LESS has been shown time and time again to actually make workers more productive

As you said, you can’t measure productivity by simply counting the hours worked. Resorting to such crude metrics is a sign of incompetent management done by people who have no idea whatsoever how to determine the result of the work they are supposed to be organising. I’d say it’s a symptom of a managerial caste that has only learned to cosplay as hard working by doing meaningless bullshit work for 60 hours a week, but whose only actual competence even remotely related to productive work consists of reading the clock.