Oooh yes. The distinction between "backup" and "archive" is important.
Backups generally are short lived, whereas archives can sometimes last decades.
The company where i worked on backups thought that an archive would not be required. We backup on tape anyway, so why not keep one full set every half year for "forever"...
There where so many damn dependencies in the system...
To start with, obviously, tape drive generations. LTO could, back then, read two generations back. But when the first generation of tape libraries was due to be replaced, we went with LTO-4. The "archived" backups where on LTO-1... So we had to keep the old tapelibrary in storage.
But that was not all. At some point we got a big SAN storage. That came with new backup software that was incompatible with the old backup format. Yay, we now also keep the old server alive
The hardware of course, since the old tapelibrary is connected via SCSI.
But even *that* was not all yet. That new backup software used a special protocol to backup the data, called NDMP. That is neat and more importantly, with a capacity nearing the Petabyte range, fast. But that protocol introduced yet another dependency: Restores are only possible on a compatible storage. Guess what: a couple of years later we got a new storage, with incompatible NDMP...
And that is not yet touching stuff like integrity testing, or even compatibility of data formats.
A proper archive is *hard* and expensive. A backup with a defined data retention policy is almost trivial compared to that. Apples 180 days are, in my opninion, on the long side for backup retention times.
I have not used the iCloud yet. Does Apple notify the users about imminent retention expiry?