What is the purpose of the narrator's disclaimers in Irving's "The Devil and Tom Walker"?

The narrator of "The Devil and Tom Walker" sometimes reports events by starting with "It is said that..." instead of just stating straightforwardly that the event definitely happened. Even more oddly, the narrator makes quite a few statements that seem like disclaimers as he reports the story.

For example, as Tom meets the devil for the first time in the woods, we're told how their conversation went, and then the narrator adds: "Such was the...

The narrator of "The Devil and Tom Walker" sometimes reports events by starting with "It is said that..." instead of just stating straightforwardly that the event definitely happened. Even more oddly, the narrator makes quite a few statements that seem like disclaimers as he reports the story.

For example, as Tom meets the devil for the first time in the woods, we're told how their conversation went, and then the narrator adds: "Such was the opening of this interview, according to the old story; though it has almost too familiar an air to be credited." He's basically saying, "Well, that's how they met and that's what they talked about, but maybe you won't believe it, since it seems like any old story you've heard before."

Shortly after that, instead of just telling us what happened to Tom's wife, the narrator says this: "What was her real fate nobody knows, in consequence of so many pretending to know. It is one of those facts which have become confounded by a variety of historians."

So, what is the purpose of these disclaimers?

They're meant to establish a feeling of realism and authenticity. Irving wants us to get lost in the story and to feel that it's really true, which ups the spookiness and suspense. Think of how your heart pounds as you watch an upsetting news story compared to how you'd feel about reading a fictional tale about the same event. That's what Irving is going for.

By telling us, in essence, "Well, I don't know what happened exactly right then," and "People disagree about this point" and so on, the narrator comes across like a dutiful historian who reveals the inevitable gaps in his knowledge of the events and therefore, surprisingly, makes the whole account sound more realistic.