Non-revenue generating back office works? "Human Resource Management is a cost to the company"?Share your opinion!

I can see the answer in your question itself, That's why they stopped calling it "Cost Centers" and they called them Non-revenue, this means that it is no revenue generating but still essential to control and manage other costs elements efficiently.

Taking the HR as an example , The HR role will start from hiring the right person with the proper cost (Not only the least cost), Train the employees to increase efficiency, Manage the incentive scheme to keep the employees motivated and to reduce the employees turn over and many other  tasks that affects the company's performance results and profitability.