No, not just DRYing (at least, not in my opinion). There should be a real separation of concerns/division of responsibility. So the direct controller "only" c

No, not just DRYing (at least, not in my opinion). There should be a real separation of concerns/division of responsibility. So the direct controller "only" coordinates the model, view, and services. I put it in quotes because there's still a lot in there (which should be organized as well): changes coming from the model, UI events from the views, and events from each of the services involved. Well, I guess you can call all of that DRYing, but it is definitely a deeper activity than just factoring out repeated code. There's real design to be done, to determine what the key concerns are exactly and how they compose to form your app. (Put another way: you can superficially factor out repeated code and still end up with a soup of interconnected services, controllers, models and views with a variety of communication mechanisms between them.)