You see this same situation with large and small legacy systems that have reached end of life and need to be replaced. In some since the app or system can serve

You see this same situation with large and small legacy systems that have reached end of life and need to be replaced. In some since the app or system can serve as the requirement for the replacement, but no one ever sees it that way. Why is the rewrite late? Still waiting for requirements! That running system over there is your requirement! Wait, that old crap? Yes that old crap.