[eaa]

First of all, if there is no documentation then it's not engineering.

If you don't agree, then imagine civil engineers which don't bother writing documentation, or mechanical engineers not bothering to do blueprints, or electrical engineers don't bothering to document schemata, properties and behaviour of components, etc. Would it be a work of an engineer?

The biggest problem with SW documentation is that people don't know how to do it properly and even why to do it at all. Mostly because people in universities also don't know how to do it properly and so it is not taught. As a result the documents are often a mix of useless prose with some incomplete and imprecise diagrams. That's why most people don't bother.

David Parnas makes it clear WHY and HOW to write documentation for SW.

If you wonder how good can documentation be then google "requirements document for A-7E aircraft". Barry Boehm has said that it's the best requirements document he has ever seen. I guess that it's still the best one!