You might be right from a purely theoretical perspective, but through the way the ActivityPub federation mechanism works, there' will be an inherent difference

You might be right from a purely theoretical perspective, but through the way the ActivityPub federation mechanism works, there' will be an inherent difference between local content (in easy reach on the same server) and remote content which would require additional HTTP requests to make sure you have the latest versions of the objects related to it (authors, recipients, etc).