And the mere fact it's a default makes it a significant problem when discussing it as a popular and widespread E2E messenger. It would be more borderline if it was a required configuration choice with no default that clearly disclaimed the ramifications.
Even then, you have the issue that you are not the only person with a copy of the conversation. Your partner - or partners - has it too. Does Apple require some kind of pre-conversation negotiation to determine how the conversation will be stored in the backups? Or at least provide some kind of warning if a person with backups disabled gets in contact with somebody with backups enabled?
I don't disagree with you about backups, but how useful they are is completely irrelevant in this context for several separate reasons.
Users need backups to protect from a device loss scenario. Apple needs to have keys for that to work. They also can’t rely on key derivation because users forget their Apple ID passwords all the time.
It is relevant because this requirement necessarily conflicts with strong e2ee. And since Apple is designing devices for end users that don’t necessarily even know or care what e2ee is, it seems completely reasonable to have defaults that will optimize for the problems that are relevant for the majority of users (losing decide and forgetting your password) while making strong e2ee a few clicks away to those who need it (and understand associated tradeoffs).
And the mere fact it's a default makes it a significant problem when discussing it as a popular and widespread E2E messenger. It would be more borderline if it was a required configuration choice with no default that clearly disclaimed the ramifications.
Even then, you have the issue that you are not the only person with a copy of the conversation. Your partner - or partners - has it too. Does Apple require some kind of pre-conversation negotiation to determine how the conversation will be stored in the backups? Or at least provide some kind of warning if a person with backups disabled gets in contact with somebody with backups enabled?
I don't disagree with you about backups, but how useful they are is completely irrelevant in this context for several separate reasons.