> Scalable, robust, adaptable software is only a requirement because it was previously infeasible for individuals to build non-trivial systems for solving any more than a one or two personal problems. Even software engineers couldn't write their own text editor and still have enough time to also write software.

That's a wild assumption. I personally know engineers who _alone_ wrote things like compilers, emulators, editors, complex games and management systems for factories, robots. That was before internet was widely available and they had to use physical books to learn.