[auggierose]

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.