[Shifted this to its own thread to as not to increase the neutron cross-section. Also this is going to get quite long.]
I think it’s a different sort of target.
Do you want to tell a spare economical story, or do you want to create a world that people will engage with? Chekov was writing about plays set in the real world, in an era when drama favoured minimalism: one interpretation is simply that you shouldn’t call for any props on the stage that distract attention from the ones you’re going to use.
(Note also The Cherry Orchard in which there are two un-fired rifles, supporting the overall theme of futility and incomplete action.)
To many science fiction readers, part of the fun of the story is working out the puzzle of what’s going on in the world without having explicitly explained. (Non-SF-readers meeting a narrative of this type will often be confused - if you don’t do the puzzle-solving thing the story can seem arbitrary and random.) I see this as analogous to reading mysteries, in which I’m both enjoying the story on its own merits and playing the game of whodunnit.
If the story is set in the real world with normal people, you don’t need to build their fascinating complicated world because all of that’s been done for you. But if it’s not, whether that’s a technothriller with manly special forces types or SF or fantasy (though I’ll come back to that), you’re introducing people to a setting that’s not the one they live in. And one way to make that setting feel real is to give the impression that there’s more of it than the words you’ve put on the page. People make a passing mention of that thing they did back in the day, without explaining it, because a real person in that situation wouldn’t explain it. And while the diegetic reader may be confused, the puzzle-solving reader will pick it up and look at its context and make it a piece of their jigsaw. It becomes part of the structure of the world that the reader is building.
Coming back to SF and fantasy, though, both have a common setting now. The writers of The Encyclopaedia of Fantasy called it “genre fantasy” because the editor wouldn’t let them call it “rotefant”. The familiar fantasy world, farms, villages, towns, probably elves and dwarves, wizards, dragons - it’s lots of pre-1970s fantasy funnelled down through D&D then spread out again through authors who hadn’t read the originals but did like D&D. Each book may have its own twist on the recipe, but the core recipe is there, and familiarity is important – part of what the reader is there for is an escape into a world that won’t be too surprising. (This sounds dismissive, but it really isn’t meant to be.) Romance and mystery can work similarly, though there the familiarity is more in the shape of the plot: hero and heroine will get together in the end, the killer will be caught.
These days there’s also a generic SF, a blend of Star Trek (a little bit) and Star Wars and Firefly. Jessie Mihalik’s Consortium Rebellion trilogy is an example of this: we have interstellar society and spaceports and one-terrain planets, and one person can steal a spaceship and fly it somewhere. Again there’s stuff that’s specific to the setting, but there’s a very familar base which eases the burden of getting into the story.