I can't readily tell how much of the dumbness is from the filesystem and how much from the kernel but the end result is that until it gets away from 1980s version of file locking there's no prayer. Imagine having to explain to your boss that your .docx wasn't backed up because you left Word open over the weekend. A just catastrophically idiotic design
Ah but this is really not true. Volume shadow copy makes snapshots of files and through that it can make a backup of an entire NTFS including files with a lock on them and fully quiesced. It was invented for that exact purpose. Backup software on windows leverages this functionality well. It took much longer for Linux to have something similar.
I have many criticisms of NTFS like it being really bad at handling large volumes of small files. But this is something it can do well.
The lock prevents other people from copying the file or opening it even in read only, yes. But backup software can back it up just fine.
I can't readily tell how much of the dumbness is from the filesystem and how much from the kernel but the end result is that until it gets away from 1980s version of file locking there's no prayer. Imagine having to explain to your boss that your .docx wasn't backed up because you left Word open over the weekend. A just catastrophically idiotic design