The file-level deduplication [1] is interesting. Not being a filesystem expert, this sounds like it fulfills a similar usecase to snapshots [2]. Or am I reading this wrong?
NTFS Shadow Copies are more like LVM/ZFS snapshots than APFS's file-level CoW snapshots, in that they both operate on the entire volume at block-level, rather than having a per-file level of granularity.
There are other FSes that allow the behavior that APFS is demonstrating - look at OCFS2 and Btrfs, both of which allow you to do cp --reflink.
There are other FSes that allow the behavior that APFS is demonstrating - look at OCFS2 and Btrfs, both of which allow you to do cp --reflink.