What you're talking about looks like (is...) dependency injection. Rails is a response to the Java FactorySingletonWidgetFactoryClass culture, so the question is does DI benefit Rails, or simply allows us to pontificate about our code? Which is what DHH is arguing against.

In my experience DI has been a great pattern for writing testable code, so do you have any resources relevant to DI in Rails, and why it (DI) is more beneficial than the OPs argument of a Service based architecture? (other than a simple google search like I did?)