Leaders doesn't always just mean project managers either. In software it can sometimes be the senior software developers that you have mentoring, training, and providing oversight on the junior software developers.

And I'm glad he addressed the "more people means more production" because that's not just not universally true. More people can lead to less production. You might have to retask senior employees to bring junior employees up to speed, so you lose production until the point they can work independently. Or if you bring in new management, you might create more management levels that can blockade things getting done. My company follows the Lean philosophy and while sometimes new headcount is the answer, sometimes it's also a change in processes. And we try to fully understand what the effect of a new person is going to be on all elements of the process before we arrive at that conclusion.