Programs need to separate users’ workspaces from each other. Imagine every time you wanted to write something down, and another person was also given access to your paper to write. Not only would there be a conflict between the two writings, but the other person can see what you wanted to write, and you can see their writing. This is insecure and confusing for end-users, like this cat.
Tap the Process Isolation link above to learn more about it!