"Never" is a tiny bit harsh, IMHO; arguably, there have been several of them they just (evidently?) don't offer content producers as much value as it offers to consumers (which includes search engines), and thus the incentives play out in exactly that way

* JSON-LD markup exists in plenty of modern sites

* schema.org markup exists in some

* microformats.org briefly raised its head

The BBC website is the biggest example I know of which has a lot of semantic markup/annotations. IIRC they used to actually have RDF attributes in a lot of the BBC Radio listings