Semantic Web is a field that is obsessed with theory, without producing any useful theory, nor any practical artifacts that can be used.
Hating entire fields is an entirely reasonable thing to do when they are not productive and when they draw attention away from more useful activities. And it's quite possible for social dynamics to do that, for the wrong thing to become en vogue, and for really wrong paths to be followed for long periods of time. And it's entirely possible to study something that's actually nothing, such as alchemy. Perfectly fine to hate the field of alchemy.
http://linkeddatafragments.org/ - allows to query several "semantic web" datasets at runtime by issuing several concurrent HTTP requests
http://www.rdfhdt.org/ - allows to store graph-like data in a very compressed format that is queryable directly in memory
http://events.linkeddata.org/ldow2015/papers/ldow2015_paper_... - (shameless plug) allows you to query and browse semantic datasets (hosted by different people on different servers) on the web using keywords
The fact that they're not useful to you does not make the entire field useless.
Foundations such as query federation, graph compression (HDT), reasoning, data integration and much much more.
So out of all of that, RDF and MathML are the only things that even attempt to define any kind of semantic encoding, and as far as I can tell they completely fail at that in the real world. For the vast majority of real world services, if you want to extract semantic data out of them you use JSON.
JSON is just the encoding, not the data model; it doesn't work at the same level. That's why RDF/JSON and JSON-LD exist.
Without disputing the idea that the implementation of the Semantic Web is a failure, this idea that JSON (or XML, for that matter) is a data format is holding us back. Every provider is saying that they output in a "standard" format (JSON), while we keep writing new clients for each and every service out there, because every data format is different and it's impossible to write common handlers.
Except for a few attributes, a Github user and a HN user could have the same structure, since conceptually they're quite similar concepts. Yet, try handling [1] and [2] with the same code.
The regular claim that programmers can handle more abstraction than regular people just sounds like a sad joke whenever I think about the shortsightedness and lack of self-awareness that has led to the current situation.
[1] https://hacker-news.firebaseio.com/v0/user/jl.json?print=pre...
The only piece of data that seems in common is that they both have user names.
There is no reason user data should be similar across different systems. Products are generally unique, or they don't have much value. That means the data tied to a user is often also unique.
This is what RDF allows you to do: instead of designing a custom format, or being tied to a rigid standard one, you can simply add standard attributes to the element in an ad-hoc fashion, so the client can use whatever attributes it supports while allowing for the ones it doesn't. And if there is no standard attribute, fine, you can add custom ones as well.
There's no reason the same code shouldn't be able to process HN, Slashdot and Reddit threads, for example - and even a Github issue.
The parent post said "they provide" but it was referring to multiple fields.