A few problems I have with this: There’s a large body of sci-fi work that asks the question, “What if our universe were exactly the same *except* for this one thing?” and by exploring the question, by thinking about the consequences of the change, we find out more about our own universe
Sci-fi depends on claims about what technologies the natural world will allow under the existing physics of this verse. Fantasy says "this universe is irrelevant, imagine a different one"