What is the benefit of nanosecond granularity? Apple recently announced a new file system for Apple products, Apple File System (APFS).  Amongst the characteristics, is Nanosecond Timestamp Granularity. Sure, this sounds impressive, and is a great improvement compared to one-second granularity of HFS+.
Lee Hutchinson writes that:

Nanosecond timestamps are important in a modern file system because
they help with atomicity—in a file system that keeps a record of
writes, having nanosecond-level granularity is important in tracking
the order of operations.

How does nanosecond granularity improve my experience as a user of Apple products?  Or is something I'm not likely to notice?
It makes your file system less likely to lose or corrupt data if it is shut down incorrectly, e.g. by turning your computer off instead of shutting it down. It doesn't affect the user experience except for making your file system more reliable.