I think from the book "Show Stopper! The Breakneck Race to Create Windows NT and the Next Generation at Microsoft" by G. Pascal Zachary he mentions that NTFS was developed by an intern for the Microsoft PC system, on hardware that wasn't entirely finished, so, inexperienced file system developer + raw unbaked hardware + time pressures. This is going on an old memory, I haven't read that book since the late 90's.

Also throw in the fact that its proprietary and there is no specification or official test suite that I'm aware of outside of Microsoft.