I need something explained to me.

Why is it important that everything get shredded? I don't understand this. You give someone a shredder by their desk and every piece of paper they don't want anymore has to be shredded. Why!?! Can you not put it in a recycle bin and maybe use it as scrap paper? Or just leave it a refuse piece of paper? What's really accomplished by shredding it into little strips? I don't understand this.