And for good reason they don't gain widespread adoption. E.g. schema.org is barely used outside of making your website better scrapeable for Google - it is an (indirect) Google project after all.
The only "core" ontologies that have really found adoption over the decades are the ones that everyone is forced to use as they are baked into the standards (RDF/RDFS), and Dublin Core for metadata (where only 5 of the ~100 terms are commonly used).
The only "core" ontologies that have really found adoption over the decades are the ones that everyone is forced to use as they are baked into the standards (RDF/RDFS), and Dublin Core for metadata (where only 5 of the ~100 terms are commonly used).