Yeah the fear that in the end everything will crumble and be absorbed by darkness is a common fear in the real world too so this creating the Yami, which Blackbeard called the most evil and dangerous in the world, fits very well For the power.
I think these concepts come in the form of devil fruits. Which if this is the route Oda goes, I’ll actually like this growth of devil fruits. (Even more so when you think that Brooks fruit would be from a fear of a zombie Apocalypse)