The narrator is a third person omniscient, able to weave in and out of different characters' thoughts. This omniscient perspective also enables the narrator to make generalizations about the public or society. Though the narrator may know everything about the story, that doesn't mean he tells us all of the details about the story, like why, for example, hunger artists became unpopular.
Having a third-person narrator also means that we don't get to hear the hunger artist tell his own story. What would the story be like if the artist were the narrator? What might it add to the story? What would we miss (we're thinking the bit about the panther…)?