If you make a git repository on your machine and then delete the entire directory it is in you can not recover it despite git being DVCS. If you have 2 forks of the repo stored on the same disc as the upstream repo and that disc dies, you lose everything.

You’re conflating offsite backups, a type of backup, with the class of backups. Backups can be on-site. Is it as durable? No. Is it a backup? Yes.