Thank you, outstandingly well reasoned and explained. I understood the incentive issue. No manufacturer of a thing, that makes money per thing they manufacture, is incentivized to try and reduce the number of those things they get to manufacture. But the fact that the optimization process towards efficient rockets leads the design away from optimizations for re-usability (principally towards a single large engine on the first stage) is new to me.<p>The fact that the Falcon 9 is deliberately designed for less efficiency with 9 engines on the first stage, but still ends up cheaper than the alternatives is even more impressive given that insight.