Yet another lesson one can learn from evolution. Features that are not important anymore are removed fairly quickly. On several occasions breeding has resulted in the loss of some features as the process was focused on other things to be. This can have a negative impact: Understanding which features are those you want to keep and which have to die is pretty vital. As to the deleted code: There is always the Source Control (DNA) Why comparisons to manufacturing should fail would have to be explained to me. Software making isn't just a pure thought process. There is a result, compiled software that does things, can be distributed and shows resistance to change. There are constraints, not only in requirements, but in hardware and infrastructure. It is not a pile of drawings, diagrams and documents or recordings of narrations describing patterns that would solve a problem.