You can't technically enforce an application to cleanly split cache and configuration data and you will probably already fail to enforce splitting application data and user data for applications that need to access user data.
Technical enforcement is also not free - it has both a performance and usability cost at applies to everyone not just bad actors. One of the things I like about free software is that it allows for high trust environments because you don't need technical restrictions but can instead rely on people not being dicks. I consider this similar to wanting to live in places where I don't have to worry about locking my doors and closing all windows every time I go to the store.
Technical enforcement is also not free - it has both a performance and usability cost at applies to everyone not just bad actors. One of the things I like about free software is that it allows for high trust environments because you don't need technical restrictions but can instead rely on people not being dicks. I consider this similar to wanting to live in places where I don't have to worry about locking my doors and closing all windows every time I go to the store.