When you create a world for your story, you will set rules. Following them makes sense. Each world whether for a contemporary romance, a historical story, a mystery, fantasy or science fiction, the author has to create the rules followed in this world. This places a restriction on the writer. Breaking this will turn a reader off. Ther second restriction also follows. Anything that happens in the story must make sense. Fiction has no room for chance happenings. It's not like real life which is ordered chaos. In fiction all chaos must be planned for and fit the rules of the world created. So following the rules you as the writer have created for your world makes the story work. Throw chance away and plan.