Wagner's MBA Law of Human Resources Department Stalking on Facebook

Wagner's MBA Law of Human Resources Department Stalking on Facebook; I realize that individuals in Human Resources departments spend a considerable amount of scarce company resources on stalking employees and potential employees in social media. Considering that stalkers rarely have training in research, psychology or therapy, would/could/should their "analysis" of you have any practical utility? Does it really help build better products/services and is it a necessary business activity? (I'm not sure.)