(Decentralized version control is only slightly different; if you lose the 'main' repository and don't have an exact clone (aka a backup), you may be able to glue together something from other repositories that is close to or equal to what you had, but there is no way to know for sure)

its rare, but sometimes a repository can get damaged beyond repair. keeping it inside of a cloud storage directory like google drive, dropbox or similar makes it prone for fatal errors.

in such a scenario a backup of the full repository is required. in gits case, remote sources can fill the 'backup' role pretty easily, as everything gets pushed to a remote server. this is obviously not enough safety if you're a bigger enterprise, they'll need additional safety guards/backups, but its sufficient for most people.