It works because most people like repetition, and putting in minimal effort into obtaining a desirable outcome. For example - Bungie makes people replay the same shit over and over, because they know it won't over stimulate people into actually wanting more. Repetition simply works, it's embedded into our whole social structure. Repetition becomes something that is merely part of your life, therefore, you're less likely to question it. Video games these days are not design as they were 20 years ago.