Why does Apple provide the "Ignore ownership on this volume" setting?
It's for read/write access on shared drives.
For example, if you have a shared USB drive the permissions will most likely not match your particular credentials.  For you to read/write to that drive, Apple gives you this functionality.
Additionally, given that you must be an Admin to enable/disable this, it doesn't exactly &quot;abuse&quot; the UNIX file system ownership principals.