> So you can't delete in-use files entirely because then they would be allocated disk space but unreachable via any path.

Isn't there a $MFT\\{file entry number} virtual directory that gives an alternate access path to each file? Wouldn't that qualify as "a way to access the file?"

Also, you might say that in practice Linux abides by the same rule - the old file can be referenced through some /proc/$pid/fd/$fd entry.