> But it has had man-centuries of work to get it where it is now; a de novo solution will necessarily need similar levels of work to get to a similar point. Th

> But it has had man-centuries of work to get it where it is now; a de novo solution will necessarily need similar levels of work to get to a similar point. This reasoning falls down in two ways: sometimes changes need to be reverted (and there's no reason to repeat those mistakes) and sometimes changes make further changes harder (and these changes can be done smarter in the new project).