The problem is essentially the following: in a know-all situation (prototype, reduced domain, startup,..) situation it is easy to ditch the 90%. No sync needed,

The problem is essentially the following: in a know-all situation (prototype, reduced domain, startup,..) situation it is easy to ditch the 90%. No sync needed, no docs needed, no tests needed, ... Once you scale up to large systems (ignore complexity) with hundreds of developers then you do and can not know it all. At that moment the churn starts. And unfortunately, once you get big, regulators, lawyers, audits and other things become a drama as well.