Rather than being an issue of credibility, I would say the biggest
reason that id.loc.gov is getting relatively little use is because the
communities that it's designed for aren't using it: libraries.
LCSH authorities aren't terribly interesting to non-library
communities by themselves. They have simpler or more appropriate
domain-specific thesauri to describe their data. What is interesting
to non-library consumers, however, are the resources we've described
with these subjects. Then when these subjects are related to their
subjects, we have a rosetta stone of sorts.
I had written a rather long reply to an earlier message of yours, but this is a better place. Essentially, I wrote that I was surprised to discover that you were absolutely right and RDF does not have the flexibility I think is absolutely essential: to break the headings into individual parts and in this way, to allow all kinds of new and even exciting possibilities. Otherwise, we are remain stuck with the same old textual strings that gave our patrons such trouble in the past, and now they are simply being "rewritten" in RDF. By this I mean there can be no links from Italy, Northern--Civilization to Italy, Northern or vice versa, and the only way of bringing them together in a coherent fashion is to throw the user into a left-anchored browse display, which of course, is exactly the same functionality as the card catalog. (And this without the much superior displays offered by the red books) As a result, it seems as if we are in a less flexible situation than perhaps ever before. I don't understand why RDF cannot do this, but it really doesn't matter.
While this may have been well-known and obvious to many on this list, I am a not an expert in everything, so this realization has come as rather a shock to me. I find it exceedingly tragic for the cataloging world and the library world by extension, but I confess it does appeal to my rather twisted sense of humor--it is highly ironic that we are still stuck with the 19th-century world of textual strings (that is, we lack the correct tool, so essentially the situation is that although we need a powerful electric screwdriver with multiple bits, all we have in our toolbox is a hammer). But it's also tragic since I don't see any solution.
To return to the point of this message, I think that the reason id.loc.gov isn't used is because it is providing people with something they neither need nor want: it provides a tool that is already passe (textual strings with obsolete navigation). No one will ever use it because even if they do, it is a tool designed for another era, a time that has been gone for at least 15 years (which is a *long* time in modern information terms). Why would even a library use it since the public doesn't like the traditional functionality in the OPACs today? I can't imagine any web designer using it except on some sort of theoretical project, since dbpedia and other tools offer exactly the same functionality plus a lot more (and the designers can even add subjects themselves).
Please correct me if I am wrong, but if all we can do is provide 19th century browse displays of our headings--and headings are the vast majority of the control we exert over the records we create and the materials in our collections--we can do that right now and it is met by incomprehension and uncaring on the part of the public with the result that they ignore our tools whenever they can. I don't see that changing now.
Is there a way out of this? Or should we start working a lot more with dbpedia?