"Online only" default option for app--completely useless?

I set up the dropbox app on my PC, and followed the instructions to make the attendant folder treat everything I put there as online-only by default. As the instructions say, "This setting means that all future files and folders that you add to the Dropbox folder on your computer will be online-only." Clear enough, right? Except whenever I copied and pasted a file into the folder (I need the originals to live elsewhere, and don't want duplicates taking up space), it was offline, with the green check. I did everything I could to make it work, gave it time thinking maybe they would switch after a bit, and then finally noticed this caveat at the bottom of the instructions they give to make online-only the default:  "Note: If you create a document directly on your computer and move it into your Dropbox folder, it’ll still be available offline unless you manually set it to be online-only." What? As opposed to what?! Moving items I created (or that just exist on my computer period) into the dropbox folder is the only way I have to put them in there! So what is the point of the setting that I want files I put there to be online-only? What else would they mean by "all future files and folders that you add to the Dropbox folder on your computer," if not these? Please tell me what I am missing and what I can do to make this work properly. Thanks very much!