Nice summary. Sure, for millions of people the 30 day retention period for deleted files is fine. However there have been a number of posts (in the handfuls?) where people have lost iCloud data, usually pictures. I would argue that encouraging people to use it as their backup isn't a great idea. I don't want to see anyone, even 1 in a million, losing data. For that reason my position is to state that it is not a backup service.
Thanks! We could go back on pros and cons forever, of course.
30-day retention period for deleted data, imo, falls outside of "backup" as well. While you can certainly use a backup scheme (including Apple's own Time Machine) that does retain older data/versioning, it is hardly a standard feature of 3-2-1 or data-reliability methods like mirroring or RAID. To my line of thinking, "backup' is for recovery from catastrophic data loss - hardware failures/loss, fire and flood, malicious attacks, accidental erase/format, etc. Saving the end-user from day-to-day mistakes is something else. If 30 days recovery from an accidental Delete is considered inadequate... Just how far do we have to go in saving people from themselves? How much discarded data has to be saved on the chance it will be needed, and at what cost? Should an undo buffer survive a system reboot?
I also think it's reasonable to assume that some percentage of reports of iCloud data loss will come down to user error/omission rather than system failure.
The question of whether classic 3-2-1 or iCloud is more reliable is very open, as far as I'm concerned. First, the number of people who follow that 3-2-1 discipline is a small percentage of the total user base. Any data protection scheme that requires user action (say, transporting a backup drive to the bank vault on a monthly basis, or connecting an iPhone to a computer to sync/backup) has a reliability problem. Even automated/semi-automated methods have their weaknesses - ignoring messages that one must buy additional cloud storage or update the payment method, external drives that become disconnected, maintaining a network connection, etc. So holding iCloud to a 1-in-a-million standard while assuming traditional backup will be flawless...
The best laid plans of mice and men are still subject to Murphy's Law and basic human fallibility.
In the end, any form of data protection (like most things in life) is as good as its execution. We're splitting hairs when it comes down to which method is potentially superior. What matters most is that something is actually
used.