The easiest path with JSON is to do none of this, and so the majority of teams (particularly inexperienced ones) do none of it. With protos, someone must at least sit down and authoritatively outline the structure of any data being passed around, so at a minimum you’ll have that.

But even just forcing developers to do this generally means they start thinking about the API, and have a much higher chance of documenting the semantics and cleaning up parts that might otherwise have been unclear, confusing, or overly complex.