Documents Library capability has been a source of confusion for app developers from the first days of Windows Store. This capability can be easily set through App Manifest editor to enable the app to access user’s Documents library through WinRT API. Although it perfectly works during development, enabled Documents Library capability means almost automatic failure of the Store certification process for the affected app, when the app is submitted using non-company account.

So, look what is missed in Visual Studio 2013 Preview App Manifest UI:

Documents Library capability is gone and all attempts to access this folder will generate exceptions:

However, this capability is gone just from the UI, you still can open appxmanifest source and manually add the capability. The result will probably be the same as before – failure of certification for individual developers, so you better stay away from this trick. Microsoft strongly recommend against using Documents Library capability, suggesting Folder and File Pickers instead.