You can turn every be-group into a role. And then switch between your roles. When you have activated role B, then role A, C and D are "detached". It's like A,C and D are not assigned to the user.
Because a role is essential a be-group, you can define webmounts, filemounts, which modules and fields should be accessible and more.
This means a less cluttered backend, especially if you have many extensions installed and/or many different sections on your website.