I can see where you're coming from, and your point of view is certainly not baseless, but I just thought I'd point out that at least Google has pushed for the development and adoption of linked data formats like JSON-LD [0] and standardized vocabularies like schema.org [1]. They make use of it for "knowledge graph" [2] features, as well as in Gmail for what they call "actions and highlights" [3] (things like displaying flight reservation details, for instance).
Yes, Google would love for you to mark up your data so that they can better consume it. But good luck trying to get Google to make any of their data more interoperable. Google Plus, YouTube, Google Photos... they do have somewhat limited APIs, but they are not federated and standardized. Semantic web in, limited proprietary access out. Walled gardens are a business tactic, no semantic web technology can change that.
I think you are correct. Semantic web is a decent technology. It has some rough edges, but it has solved the technical aspect of the data interoperability problem. The only barrier is a social/political/business one: privatizing and monetizing user data is the business model of most of Silicon Valley. I always say that a federated protocol like email would never be adopted today, the business incentives just do not exist.
[0] https://json-ld.org/
[1] https://schema.org/
[2] https://developers.google.com/knowledge-graph/
[3] https://developers.google.com/gmail/markup/getting-started