More generally, in the realm of physical production, where scarce resources are critical inputs, each additional unit of output is usually more costly to produce than the previous one; that is, production, at least eventually, is characterized by increasing marginal cost. By contrast, in the realm of conceptual output, much of production is characterized by constant, and perhaps even zero, marginal cost.
Of course, that is not to say the framework cannot be improved in any way. Over the course of the past 20 years or so the framework has evolved to reflect lessons learned and is likely to evolve further in response to new developments. In particular, our monitoring of monetary and credit information has increased in the wake of the global financial crisis.