In decl_auth, roles are always statically assigned to users. On the other
hand, permissions are granted based on object permissions. In your case,
those users might be globally authors, but would only have write permissions
on articles where the article's owner is the user. So, yes, this is a
standard use case of decl_auth.
Have a look at the demo app for examples:
http://github.com/stffn/decl_auth_demo_app
Steffen