What you mean is the unique name assumption, which is distinct from the OWA, and may be viewed orthogonally and applied or not applied in different RDF contexts

What you mean is the unique name assumption, which is distinct from the OWA, and may be viewed orthogonally and applied or not applied in different RDF contexts. The problem with blank nodes is that they circumvent the UNA in every scenario, and you need something like "reified blank nodes" to resolve this, a.k.a. by using UUIDs treated as blank nodes. See the following paper for a more in-depth discussion on the topic https://aidanhogan.com/docs/blank_nodes_jws.pdf https://aidanhogan.com/docs/blank_nodes_jws.pdf