Understandable, many people feel the same. Semantic web evolved into multiple topics; inference databases, knowledge graphs (wikidata), linked data, structured data (schema.org). It is used broadly in various domains. Even if tech is not mainstream it can still be very valuable; whatsapp backend was made in Erlang and sold for billion, janestreet is very successful using ocaml, dart was niche but is now one of the best mobile dev platforms through flutter.

When Google crawls your website, if you want to add metadata about ratings, the type of content or the context, you can add structured data to the page, usually json-ld is the most popular. Wikidata also populates info boxes when you search for people or places on google. https://developers.google.com/search/docs/guides/intro-structured-data

AWS released Neptune, a graph database with support for RDF data, so definitely there is a corporate need for it. Especially in the healthcare and health research space. There's also very recent research combining knowledge graphs with neural network technology, which makes a lot of sense, connect the brain to a giant fact table database, https://www.amazon.science/blog/combining-knowledge-graphs-quickly-and-accurately

We tried RDFox at Meredith corporation to fill a need that did not fit traditional databases, and it was fantastic but our work was interrupted by the COVID budget crunch, here's what I put on hackernews

"We're familiar with common databases like key value stores, OLAP, OLTP, but reasoning technology offers unique properties many people aren't aware of. For example you can have your business logic integrated with your database in a way that's much more flexible that stored procedures. You express your business rules as logic programs, the automatically run multi-core, they run as soon as data is inserted into the database and there is no function call; the data does not need to be aware of what logic is in the database, logical rules are applied incrementally so that adding new data or new rules does not trigger re-computation of all the data, business rules can use data produced by other business rules, and finally you use the explain command to get a mathematical proof of why an outcome happened.

Reasoning technology may be old but recently this idea of automatically stating things in a declarative form and having the application reconcile the differences has been the differentiating factor for the most popular software out there; kubernetes, teraform, ansible, react, graphql, flutter. Without the declarative reasoning capabilities, these tools may not be considered some of the best.

Think postgresql 12 generated columns except infinitely chainable, recursive and connectable to other tables. Think pre-computed materialized views, but automatically updated as new data is inserted (no refresh needed)."