Sometimes, you leave your desktop or laptop with a document open in LibreOffice. Then, accessing the system remotely, you want to do something with the file; it could be moving it, or even editing it both not in your running LibreOffice. At the moment, there is little you can do. I would say nothing, but there actually are ways to simulate keystrokes from the command-line. Still, that an unreliable hack. I would like for LibreOffice' command-line to let me Save-and-close one of the files that are open with LO (or with the saving being optional).
A Python script which achieves something similar: https://github.com/thomasa88/lo-remote-close
More generalized you expect UNO interaction via command line... I don't see this flying. At least there is no unique process ID for documents or even modules. => needsDevEval