The 'do one small thing and do it well' philosophy is at least contentious in the general sense. Reality: no unit exists outside the context of it's ecosystem.

The 'do one small thing and do it well' philosophy is at least contentious in the general sense. Reality: no unit exists outside the context of it's ecosystem. Ergo, the API to that unit, and the degree to which it integrates with the other pieces is paramount. The 'do one thing and do it well' ideal implies almost a kind of 'unit sovereignty' that in many cases does not exist. In large, complex systems, 'units' can only view as parts of a greater whole. 'What they do' is almost less important than 'how well they fit'.