I think this quote from an article titled "More Than Words" nicely describes some of the goals behind library linked data:
... Over the past decade, a bioinformatics specialization called biomedical ontology has grown up around this question. Most biomedical researchers are familiar with standard terminologies, such as Medical Subject Headings. These are sometimes called ontologies, but true ontologies are more than just controlled terms. They capture, in a logical, systematic way, what scientists regard as the basic truths about a topic. Like equations in physics or axioms in mathematics, they can even be the basis for computational models. When connected to databases, scientific papers, and software applications, ontologies "help cope with the ever-growing, chaotic accumulation of text and facts" in biomedical and translational research. They do this by making data sharing, retrieval, and validation easier, says Stefan Schulz, a professor at the Medical University of Graz in Austria.