[General Questions and Answers] TheMystic:
Less than 2% of Android users install a custom recovery and/ or root their device. And a much smaller number use ADB to take care of a few things on their non-rooted device. I'm talking about backup solution for the remaining over 98% users.

Pretty much everyone knows how to backup their stuff. It's just that there is a lot of work to do and requires patience. An automated backup solution helps in saving plenty of time and unnecessary work for the user.

There are, however, some situations where the user is helpless. I was playing a game for a long time, spent a good amount of money on in-app purchases, and when I bought a new phone, there was no way to transfer all that stuff. That game provided no means (either using Google Play Games or Social Media integration) to backup the user account. I wrote to the developer several times, but never got any response. I even complained to Google, but nothing happened for a pretty long time. I stopped buying stuff in that game. Many months later, the developer finally allowed saving game data to Google Play Games. Although I could now move my stuff to my new device, it was just too late. I lost interest in that game. In my case, I still had the old device with me, and working fine. So I could save all my details to Google Play Games. Imagine if someone lost their device, or broke it, or sold it...for them all that money spent in that game would be gone.

'As with your scare me to death' statement, I think you haven't understood how backup & restore works on iOS. iOS will wipe everything on your phone, do a fresh installation of the OS, download all your apps again, and then restore user settings, login credentials, etc, which pretty much takes care of EVERYTHING. The user has no work to do here. But the system is fresh, and all the junk built up over time by both the system and the apps are now gone! It is NOT a system image and restore that will bring everything back, including the unwanted stuff. So your device isn't actually in the exact state like before. It is much leaner, cleaner and much more efficient. The exact same thing happens when you migrate to a new device. Only the things that matter are migrated, the rest are not.

Do note that the user has full control over which apps to backup, and therefore, which ones will be restored/ migrated.

If I factory reset my Android phone, the backup will only restore call logs, sms, contacts, and a few basic stuff. It will also download all my apps from the Google Play Store. But here ends the similarity. Beyond this, the user has to setup every app from scratch, with the exception of a few like Google's and Microsoft's cloud based apps. User also has to setup all the permissions for apps from scratch. There is a lot of work involved, which can be easily avoided if Android provided an automated way of getting this done.

User configuration files and login credentials belong to the user. You haven't explained why app developers can choose whether this information can be backed up or not. To me, it seems like Android has a big limitation in the way it is designed, and so is unable to provide a simple backup solution that takes care of these things like in iOS.