You’d be surprised with inheriting tech debt. Quite often there’s no documentation, the last person to log in to the system is an admin that quit 3 years ago, but it doesn’t much matter because that’s only for a direct console login which normal users don’t do when accessing the application. With tribal knowledge gone and no documentation, only when you pull the network for a bit do you discover that there was this one random script running on it that was responsible for loading up all the needed data in the current system, when 9 of the other 10 times those scripts were no longer needed.

In a perfect world you’d have documentation, architecture and data flow diagrams for everything, but “ain’t nobody got time for that” and it doesn’t happen.