It would be great to have the ability to lock down access to certain resources.
An example might be if an existing project requires taking on more content artists, but the owner of the project doesn’t want those users to have access to the whole project ( e.g. to clone it and use it themselves ). In this case, the owner can add a user but not give them access to view or edit scripts ( of course they can view the resulting JS code, but this may be obfuscated, minimised or similar, i.e. not easily editable to extend the existing project code ).
For many projects, the code is quite an important part of the intellectual property, and not everyone should have access to it.
Another example might be if the team takes on external people to edit levels only, they might lock down scripts ( so none of the new people can go in and change code in a core script by mistake, making the game un-runnable by everyone else ), and also lock down the ability to edit existing prefabs ( so the layout people can only drag and drop existing assets, not modify them in any way ).
These are just a few quick examples, but being able to restrict access to certain resources could come in handy for some team projects.