This question might seem a bit weird at first. But imagine you have build a large scene, and in that scene are a several objects that you want to send to another person without sending the whole scene. Is it possible to select some objects and the use Export —> selection --> specify target blend file, or save as new blend file?
All in all, the oposite of appending an object into your scene.
Blenders also really nice in that you can open a file, select what you want cmd+c or ctrl+c, go back to your original file and paste your selection into it.
If you just delete everything you do not want in the scene, things might still get left behind (materials, data blocks, scene or file settings). Appending or copying objects into a new scene requires you to open an empty scene beforehand. So I think an ‘export’ option might come in handy in some cases.