In typical MVC applications, people end up storing business logic into either the controller or the model layer. The problem in this approach is that in either case, you introduce code bloat and dependencies that should not really exist. Controllers, which are essentially the observer pattern, act as a traffic light, taking requests and directing them to another point. Models themselves should focus on the data within their domain. But what happens when you get complex interactions between these forces? What should you do? This is where the MOVE paradigm comes into play.