Note that some *NIX flavors do allow hard links to directories! It is admittedly highly unlikely that your friendly sysadmin would dare to use this privilege, for fear of corrupting the file system.

However, if she did, that directory would have a higher linkcount than expected, even when devoid of subdirectories.

Also note that files contained in a directory do not count towards the directory's link-count. Only immediate subdirectories do.