Never in history have companies hired more employees for the sake of having more employees. This isn't a new modern or even libertarian hypothesis.
Do you think people in 1000 bc hired more employees than they needed just maximize headcount. Of course not. You want enough to get the job done and not more.
People in 1000 BC is maybe not the best example here considering practically the entire population of Egypt was tasked with building or supporting the building of the pyramids among many other projects.
I think that's just as good of an example as any. Do you think pharaohs hired and fed more slaves than they needed to build a pyramid just to maximize worker numbers, or so the extra could sit around and take it easy?
Egypt had shops and Merchants too.
Can you think of any time between then and now where things worked that way?
Do you think people in 1000 bc hired more employees than they needed just maximize headcount. Of course not. You want enough to get the job done and not more.