Note that the article subtly admits that you can subvert the objectivity in your model-based decisions by making your subjecive choices of how to build the graph.
I think the graph itself is useful for that exact reason. It lets us see the the specific model assumptions and generate the testable conditions.
This is always true: you're always making some strong assumptions when trying to make a causal claim. Using a causal framework, DAGs in this case, at least makes those assumptions explicit.