Management has to provide the coordinating mechanism between what the supplier provides and what the user needs in not-good-enough situations where product architecture is consequently interdependent. Management always beats markets when there is not sufficient information.
The outsourcing gurus have been driving the theory, and they are saying everybody ought always to do this. But it is really contingent on where you are on the spectrum from "not good enough" to "more than good enough," relative to each tier of the market.