The use case is isolation, which is not necessarily exactly the same as reducing access. For example, maybe you don't want the process to be able to easily det

The use case is isolation, which is not necessarily exactly the same as reducing access. For example, maybe you don't want the process to be able to easily detect that it has had its access reduced, by simulating a full-access environment. Or for example, maybe you don't care about access at all and you just want to avoid conflicts between two processes by giving them separated namespaces for their data.