RDF, a W3C standard which is supposed to be the foundation for semantic web, is not obtaining universal acceptance as HTML did. Frederick Giasson analyzed some of reasons in Wikipedia concepts to help managing Semantic Web described subjects. He thinks RDF “is so beautiful and powerful is also a huge problem and probably the bigger weakness of the semantic web.”To me, granularity is another issue. We already have XML. If we use RDF and XML to define the concepts in RSS and OPML, people will find XML is much simpler. RDF will give us some benefits but it’s not a big deal in these cases. Anyway, at this time, people need standard or agreement. RDF might be more useful if people want to exchange information dynamically.
From data structure point of view, it’s hard for people to grasp graph. Tree is a kind of ok. List is much easier.