I see at least three reasons: - I want to have a DOI for something I also sell, like a book. - I want a DOI for something that is still being submitted, and I

I see at least three reasons: - I want to have a DOI for something I also sell, like a book. - I want a DOI for something that is still being submitted, and I don't want to share it yet with everybody, only a select few (like reviewers). - A previous version of your paper has a serious problem (could be an error, or containing a password you would rather not share), and you want to remove public access to it.