Correctly noted. Even degrag programs must execute using Operating System code since hardware access requires OS permissions that only the OS can provide. And then there are all those 'proprietary secrets' in the NT drivers such as features that will make current NTFS play well with future functions.

Write bare code even for FAT would be a 'task' for one person. NTFS would be a 'bear' for a team. IOW full featured NTFS for Linux - I don't think its going to happen with rock hard reliability that we require for filesystems. Best one should expect without NT internal drivers is to safely read NTFS drives. Systeminternals demonstrated how one did so quite successfully.