Even in 2015 Apple put in backdoors. They have been really good at making people believe things that are not true. E.g. from the linked post:
iCloud already protects sensitive categories of data (like Passwords, Health data, Messages in iCloud, etc) with end-to-end encryption by default.
Except that there is a footnote in Apple's security document where they confirm that Messages in iCloud is not end-to-end encrypted if you don't enable ADP and have iCloud Backup enabled (which is probably most users):
Standard data protection: When iCloud Backup is enabled, the keys to your backups are secured in Apple data centers. If you use both iCloud Backup and Messages in iCloud, your backup includes a copy of the Messages in iCloud encryption key to help you recover your data.
https://support.apple.com/en-us/102651
So, there is always a backup of Messages in iCloud accessible to Apple and thus (US?) law enforcement, unless you enable ADP and the people you communicate with also use ADP.
WhatsApp is similar by the way. Unless you enable E2E backups, they end up in iCloud/Google Drive backups and are only encrypted at rest. Of the major messengers, I think only Signal completely opts out of iCloud backups and have their own real E2E-encrypted backups.
Even most technical people I talk to do not know this and don't have ADP enabled.
There are a lot of weak defaults like that.
The original implementation of iCloud included Apple's ability to recover the data. You can view this as a backdoor, and that might be fair, but the reality is that it's also a feature in the eyes of many customers - because people will lose devices and passwords, and when Apple doesn't have the keys that means they also lose data. Many customers would rather be able to get their data back.
Apple has moved more things into the bucket of "we do not have the keys for this" over time, but pretending that this isn't a tradeoff for the common customer is disingenuous. That's why ADP exists, so that those who want to make a different tradeoff can do so.
Commenters on HN tend to be technically savvy and tend to want the defaults to be tailored to a technically savvy customer base. That's fine, but that's not a real representation of all of the smartphone users out there, and in this case Apple is directly offering the choice that they usually get knocked for taking away.