Earlier quoted context omitted.
Depending on the backup tech, that can be kind of difficult. I can't run arbitrary SQL against the database backups I've got stored in tarsnap. Nor against tape, etc. For that matter, isn't the (or one) reason for having a backup so that errant deletes don't obliterate everything?
I was always under the impression that nothing really gets deleted online.
In the long term everything suffers from "data decay". It's just too hard to keep old files around forever.
E.g. there were comments I made on Usenet many years ago. Google has previously attempted to preserve those, but they seem to be fading away into the ether. That's okay by me.