Thanks for getting in touch! It used to be that we always extracted by default and provided no other option. We made the option to simply copy a package to the destination available when we saw the increased desire to be able to copy packages to the target without extracting them.
When we created the Reference a Package feature, we thought it fit to carry over this functionality and provide the ability to copy the package without extracting it.
We do have a small section in our documentation on the Reference a Package feature. Though it does not directly answer your question it is informative.
Let me know if you have any thoughts or questions here.