It's all about metrics. That's the core reason for all of it. Someone wants jobs wanted numbers. Someone wants application review numbers. Interview numbers. Numbers metrics wasting time proof you're doing something.
Another reason is to appear fair (which is just another metric). New manager position open, but you already know who you're giving it to? Doesn't matter, you have to post the listing and follow up with everything that entails.
Is it? I just looked at the top three months for this comm and it wasn't posted even once.
Maybe pay more attention to where you are.