From the Dewey Decimal System to Mahalo

I've been thinking about an odd comment in John Battelle's The Search [p. 33] regarding the Dewey Decimal System:
The Dewey decimal system has been updated numerous times over the years and is still widely used, but its subject-based focus would be unable to scale to the enormousness of the World Wide Web.

It's a passing comment from Battelle so I'm not using it to criticize his work but I think it's fairly obvious that the Dewey Decimal System wasn't designed to address search within resources so how could it be scalable in relationship to search?  It's simply not relevant once you get past the problem of a classification system designed to deal with individual objects and move on to the actual contents.

But subject-based classification systems are eminently scalable to the "enormousness" of the Web when categorizing individual resources and allowing for multiple subject categories per resource as shown by the Yahoo! Directory and the Open Directory.

On a related note, one has to wonder if the seemingly universal shift to search replacing portals was spurred in some small part by the devolution of the Yahoo! Directory to an overpriced SEO catalog and of the Open Directory to a poorly maintained collection of inconsistent quality.

Obviously even a well-maintained directory of websites is not a search engine.  So if you've got a web directory but a search engine's what you need, just fire up a Google Custom Search Engine, have it automatically add all the links from your directory and then let them provide the search of all the sites listed via one engine that can monetize the service via Google text ads.

Though you'll have to acknowledge Google's obvious involvement, you can then flip from directory mode, make your landing page the Google search box and call your site a search engine.

Similar to the Jason Calacanis/Mahalo model.

[Disclaimer: I'm a former Open Directory editor.]