HN user
Things change; I wonder how much has changed since "very early on" -- Oracle 11g's RDF support is extremely scalable, for example. Of course Oracle is evil so YMMV, but there's nothing timeless or essential in Joshua's claims here.
There are TONS of RDF apps...On corporate and gov't intranets. For some reason or reasons, adoption has been very asymmetrical between public Web and private intranet when it comes to much of the SemWeb stack. For example, see this: http://www.w3.org/2001/sw/sweo/public/UseCases/Nasa/ Which describes a production NASA application -- expertise location tool -- for the 80,000 person NASA workforce, which uses RDF extensively internally.