> By using HATEOAS and referencing schema definitions (such as XSD or JSON Schema) from within your resource representations, you can enable clients to understand the structure of the data and navigate the API dynamically.

I actually think this is where the problem lies in the real world. One of the most useful features of a JSON schema is the "additionalProperties" keyword. If applied to the "_links" subschema we're back to the original problem of "out of band" information defining the API.

I just don't see what the big deal is if we have more robust ways of serving the docs somewhere else outside of the JSON response. Would it be equivalent if the only URL in "_links" that I ever populate is a link to the JSONified Swagger docs for the "self" path for the client to consume? What's the point in even having "_links" then? How insanely bloated would that client have to be to consume something that complicated? The templates in Swagger are way more information dense and dynamic than just telling you what path and method to use. There's often a lot more for the client to handle than just CRUD links and there exists no JSON schema that could be consistent across all parts of the API.