It is mandatory to be logged in Koha to view the link leading the list creation page. But if someone goes directly to this page without being logged in (through a bookmark for example), he will be able to create a list which will be linked with no user. This can be test with an url like this: http://***opac-url***/cgi-bin/koha/opac-shelves.pl?shelves=1
See also Bug 6631
See also bug 7310 and wiki.
*** This bug has been marked as a duplicate of bug 6631 ***