What’s clever about this particular narrative trick is that it obeys a kind of conservation of disbelief: reduce the number of impossible things your audience has to believe in by having them flow naturally from just one or two impossibilities, which you can then spend more time grounding ahead of time to make them feel more real. (The trick of grounding an impossibility is another thing entirely, but comes down to introducing it in a way that lets the audience accept it as either utterly fantastical or deceptively mundane.)