ser/de only solves parsing problems and not much else. What about using duplicate user IDs? Or maybe many objects in the system need both the employee ID and

ser/de only solves parsing problems and not much else. What about using duplicate user IDs? Or maybe many objects in the system need both the employee ID and the name (and the employee ID determines the name, obviously), and the employee changes their name, but it only updates some objects and not all? There are lots of ways data can be subtly inconsistent and a database is a big help preventing it.