Comment by dkarl
Anything you create in software should be able to fit in someone else's head. I.e., you should be able to think of it as a tractable arrangement of abstractions that let you reason about it in a precise, non-leaky way.
Those abstractions don't just poof into existence after the project is complete, though. You have to design them into the system and communicate them to the people who need them.
The abstractions also need to be precise and non-leaky enough to be useful. One of the most dangerous talents in software is the ability to create the illusion of tractability by using vague language. You can create an absolute mess and then describe it to management in a way that makes it sound well-understood. This is the most lucrative and destructive skill a consultant can have.
Unfortunately, all the market giants follow this destructive practice to rewriting 95% of all code every five years to multiply added value.