This has been brought to our attention in the past, so we actually have created a KB article dedicated to creating and submitting articles. It outlines the basic permissions needed and involved with performing this action. You can view the article at this link. You will notice at the end of the "Submitting for Review" section it mentions that simply owning/creating an article does not inherently give a user the ability to edit their article after it has been Submitted or if it is then Approved by a reviewer or person with the "Always Edit Articles" permission. Having only the "Add Articles" permission means you can create and edit your own articles prior to submission, and if they are rejected, but you would not be able to go do anything with another user's article that they might have created, saved, and not yet submitted.
Hopefully this has fully addressed your question about the "Add Articles" permission. If you have any further questions or concerns please let me know.