> Companies that do not have external customers, but write software only for their internal use [...] do not face these problems. They know who their customers are (guys from the other cubicle), what features they use. The can take a risk of deploying an improperly tested feature.

In a non-software company, this is not my experience at all.

While some end-users are local, all communication must route through distorting managerial layers. Huge swaths of features exist from fearful inertia.