But you only have to look back to Doom 3 to see the cracks in that idea. Many design decisions of that game were unpopular when it was released, and over the following years it came out that those decisions were driven by technical aspects of the engine. Where rather than the engine sacrificing for the design, design sacrificed for the engine.
So it'd be easy to make the less immediately appealing argument that they should push back on Carmack's vision when they think it's gone off the rails.
"Carmack has also admitted that the flashlight was not attached to the weapons in the original version of Doom 3 due to performance issues" ... http://www.dsogaming.com/news/john-carmack-speaks-30fps-on-c...