Arguably this is still on Apple, because they don’t let you access the full filesystem as you can on other operating systems, and in particular because an app developer may rightfully want to create a class of internal-use files that are not explicitly exposed to the typical user, but would be available to users seeking them out.
I imagine, for example, that if the internal project files for a popular video editing app were accessible, we’d see competing and/or open source apps emerge that could parse them, were the original app to become suddenly unavailable. Instead they’re just lost because your phone won’t let you access them.
Blame can be shared. The OS vendor for providing a way for applications to hide files on the user's filesystem from the user, and the application for using it instead of making the user's documents available to the user. They are both working together in unison against the user.
I imagine, for example, that if the internal project files for a popular video editing app were accessible, we’d see competing and/or open source apps emerge that could parse them, were the original app to become suddenly unavailable. Instead they’re just lost because your phone won’t let you access them.