maybe they are in a 'sweet spot'. spaceX is not on the bleeding edge of anything; rather they are optimizing existing solutions. incremental design changes, in a problem domain that has been studied for decades, and is well known, will provide results. "web dev" for an e-commerce platform will show great improvement with an agile, move fast development process.
change the fundamental nature of the propulsion, or a step change in the technology, and it may be more effective to go with an engineered approach.
'engineered approach' --> before the item is built, a very good idea of how it is going to work has been determined. using math and science.
