Multiple Private Spaces would not be a good approach if the user doesn’t want the apps to communicate (offline and online app) but wants them to have information accessible locally to the same degree.
For example, if I want google photos have network access, it would be nice for google files to not be able to connect to it. Putting files app into a separate profile would overcomplicate file management. There are many examples, just wrote the easiest one.
At the very end, I think both solutions should be implemented (Private Space AND Communication Scopes). Private Space might be too resource intensive if you want to have each app isolated, but Private Space is useful feature nonetheless.