A directory that's incomplete is almost always worthless. Many directories are incomplete but still highly useful (e.g. Yelp is far from a complete directory e

A directory that's incomplete is almost always worthless. Many directories are incomplete but still highly useful (e.g. Yelp is far from a complete directory even for cities like San Francisco, but it makes up for its lack of completeness with the quality of its entries). The question is just whether the directory is complete enough to be useful.