If there is insufficient manpower, it is often because they are building things they shouldn't. At least this was my experience.
I never knew what a corporate intranet was for until I worked at a huge company. It's for clicking around on, going back and forth, when you have nothing else to do but need to look busy.
100%. Why make hard decisions when you can just hire? A company flush with cash simply hires and lets decision makers avoid decision making.
I'd say it's not. But causality is the reverse of the GP's.
Being overstaffed is a consequence of not prioritizing the work. Either the staff grows until the important things get done, or the organization shrinks because the important stuff doesn't get done.