Date stamped data could be corrupted or erased.
Archived data may be purged. (E.g. After 1997, new files to be saved for 2 years may be purged immediately.)
Passwords may become inoperative.
Many critical systems may be time sensitive. (E.g. think of security system or elevator maintenance - interpreted as grossly out of date - and access automatically blocked to ensure security or safety.)
Consider rework burden if primary systems fail.