A decent IT department will backup your data FOR you and protect it against inappropriate access and data exfiltration. Users shouldn't be responsible for backup.

Blocking backups is (probably) about halting data exfil (keeping people from stealing data and sending it to competitors or other bad actors).

IT is likely doing backups for you.

I could be wrong about all of this, but as a security practitioner, I block backups from endpoints for this reason.

This is such an Oregon picture...