>>externally-imposed standards That is the crux of it. I've also seen teams build a complete stack - OS to App - in short order in similar fashion in the indu

>>externally-imposed standards That is the crux of it. I've also seen teams build a complete stack - OS to App - in short order in similar fashion in the industrial embedded computing world .. it seems to be that a tight, motivated team, really can pull of extreme wonders when it works right for the specific, internally-agreed-/co-created feature set. The scale aspect is actually arbitrary; but if you have a group of people who are willing to complete the stack, full-system wise, the scale is a human factor, observed after application; i.e. its not inherent to the subject of software development that there is some dividing line between the 'difficulties' of the whole system development ethos, but rather a function of the differences, and/or similarities, of the people involved, doing something with 'the' technology .. which is after all little more than a social imposition in the first place.