Wójtowicz's closing insight: stratified design — layer your system, keep dependencies downward, draw real abstraction barriers, keep minimal interfaces — applies universally. Ruby developers are already strong at the function/method scale via extract-method and refactoring patterns; the move is to apply the same thinking systematically at class, app, microservice and overall architecture scale. MVC, layered DDD, ports-and-adapters and onion architecture are all instances of this one idea with different shapes.