Yes, the automatic serialization is not a solution for the most pressing problems presented by the article -- it's just the first thing from all the things that has to be done at the boundary.
You have some DTO class that is your system typed idea about the structure of the JSON -- this class is quite useful as an implicit documentation, but it really has to stay internal to the boundary. You will use an autodeserializer to such class and then you will continue by constructing real object from deserialized data that can be presented to the rest of the application. During such construction you can validate state and return errros.
This step can be eased by some validating attributes on the boundary DTO properties, but there is always some custom logic that describes what is acceptable and what is not.
You have some DTO class that is your system typed idea about the structure of the JSON -- this class is quite useful as an implicit documentation, but it really has to stay internal to the boundary. You will use an autodeserializer to such class and then you will continue by constructing real object from deserialized data that can be presented to the rest of the application. During such construction you can validate state and return errros.
This step can be eased by some validating attributes on the boundary DTO properties, but there is always some custom logic that describes what is acceptable and what is not.