It makes a big difference. If I print out the texts I receive, it doesn't change whether the texting program is end-to-end encrypted. The same goes for backups. An unencrypted system-level backup doesn't mean that the program being backed up is failing at security.
It's bad that Apple doesn't let you encrypt your backups properly, but it's a separate issue.
> An unencrypted system-level backup doesn't mean that the program being backed up is failing at security.
iOS programs can choose how their data is backed up. iMessage isn't just getting its data stolen by iCloud accidentally. These backups are a feature of iMessage as much as iCloud. And besides, iCloud is made by the same company, it's not a separate entity.
> iOS programs choose how their data is backed up.
Well desktop apps don't. Would you say that no desktop app that saves its key can ever qualify as end-to-end encrypted?
> And besides, iCloud is made by the same company, it's not a separate entity.
I'm not convinced that's relevant to whether the encryption is end-to-end or not.
I would say that no app can qualify as end-to-end encrypted if a large fraction of users send their data to the maker of the app in a form that can be decrypted by the maker of the app, regardless of the reason.
Utterly false. Real end-to-end encryption would encrypt the backup with a key that is not available to the backup service (e.g. derived from a passphrase not sent to the server).
Of course this system has better usability, which is why Apple does it. But it's still a farce to call a system where Apple has the ability to decrypt the majority of messages "end-to-end" encrypted. The fact that it's through the backup servers instead of the iMessage servers makes no difference.
What's more, it's possible to do better without sacrificing usability. For several years Android has been end-to-end encrypting backups using the user's lock screen passcode, with protection against brute force attacks provided by hardware secure elements. https://security.googleblog.com/2018/10/google-and-android-h...