That's what entitlements are, and the App Store review is what ensures you don't have bogus entitlements.
There are entitlements that, for example, control whether or not you can read the user's message database, the entitlement has to exist so that messages app and daemons can access that database. The App Store review process automatically rejects submissions with those, and other similar, entitlements. There are entitlements that allow reading and writing arbitrary data from arbitrary applications, because (for example) there are OS daemons and services that need to read/write all of that data (the settings app can report disk usage, there's the daemons that install and uninstall apps, etc), and again those entitlements are gated by store review.
The entire trust/security model for iOS starts at the store review disallowing system entitlements, and gating even allowed entitlements on appropriate notice in the app description.
You should really read the apple platform security documentation, but to give you an idea of what entitlements exist on the system I found this one for iOS 13: https://gist.github.com/jankais3r/1f839820f83be90d419140a6b8...
Hopefully you can look at that list and get an idea of how removing the gate on applications being able to specify whatever entitlement undermines a huge component of the platform security model.
Also I don't know what you mean by bogus entitlements, if it's not meant to be used by user apps than it wouldn't be available to user apps, if the app needs to have access to a certain feature that required a permission, it would need to ask gently the OS and the OS would need to approve it (maybe even after asking the user), or the app would not simply to be able to access it, so it's in the app's interest to have the permissions laid out correctly so that the OS knows. From the previous message you seem to believe that the app could just simply bypass the dialog asking the user for permission.