At university my peer group started to use the saying "it could be worse, there could be zombies" as a way to tell people to keep things in perspective. The statement always implied two things:
- There is no situation that cannot be made worse by adding zombies.
- If there are zombies the situation is as bad as it can get. Except by adding more zombies of course.
In this question I would like to examine the first implication: what, if any, are the situations that cannot be made worse by adding zombies?
Good answers will examine in detail what would happen if zombies were introduced to the situation and how this fails to make things worse. The best answers will show situations where zombies are actually advantageous to humanity's continued survival. The zombies in question are assumed to be slow plague zombies per the novel World War Z; unnaturally mobile dead people with a slow shambling gate and a bite that kills the living, turning them into fresh horrors. Answers should assume something that generally resembles the world we know, which means that humanity, as a species with some form of society, need to be able to survive any scenario you suggest - an atmosphere of pure acid is not relevant, nor a trip to the surface of the sun.