How do you propose to solve the problem of a user's house burning down with their phone, laptop, and iPad? Tell them sorry, your iCloud backups are encrypted and now all the keys are gone?

So encrypt the iCloud backup with a password you say... Except you need a password to get in to iCloud already so how is that any different?

And for the record, Apple stores password hashes, so they don't have your password. Unless you think they are just lying repeatedly for no good reason.

When was the last time you verified the chip layouts for your CPUS to ensure there were no back doors? Didn't think so.