At the very least, the world-builder probably wants to write a hard SF or a steampunk or a faerie historical fantasy world. But at the extreme, I ran across a complaint that if you were a billionaire, there were a lot of more effective ways to fight crime than to dress up as a bat and haunt the streets of your city with fantastic gadgets, and a countering comment that, in fact, Batman is not a billionaire who choose this way to fight crime, he's Batman, and the billionaire-hood comes in to enable that. Originally he was just rich enough to explain why he didn't have a job, and to give him a contrast between his secret and super identities.
But some are harder than others. If you want to rip off a story idea with a woman who's meeting her husband after years of war-driven separation, the only thing you need is to be careful to provide no means of easy communication and still less of easy transport -- that is, equivalent to most of the world's history. One about star-crossed lovers whose problem is that one is cursed and refuses to risk marriage requires the world-building be built up around a curse (though there is some flexibility about it according to the curse, though if you want to make them not quite so star-crossed, so the curse can be coped with, there are limits there). If, on the other hand, you have a fun magical trick -- a cool way to break magic revolving about a bone -- you have to build up the entire world, especially the magic, to fit that concept.
Sometimes, like Batman, there's no way to conceal it entirely. This is always a danger to the setting, that while it can be quite fun, it still shows its seams.