What is the most likely reason an author would use the setting of a world on the brink of destruction? 

To create the main problem or topic of the story?
Maybe the book is about futuristic events of the world ending due to real issues we have now? (Pollution, etc?)
I’d say to create a drama/problem in the book that would hook a wide variety of readers in and be a interesting read for lots of people?
That’s all I’ve got! :D

Iam confused at the end of the day i can’t always get the stuff right i need more then this so i can’t u