Bigger scale allows for better efficiency.

This is dogma, not proven fact, and most people that argue this tend to use self-serving metrics and a tailored definition of "efficient". Some counterexamples: early Google was much more efficient in responding to market changes than the current top-heavy organization; small hospitals tend to have better health outcomes (both per patient and per dollar) than large chains. Tesla was able to innovate much faster than established behemoths.