Windows has a really good basis for it though, in volume shadow copy. I also don't understand why Microsoft never built a time machine based on that. Well, they kinda did but only on samba shares. But not locally.
But these days they want you to subscribe to their cloud storage so the versioning is done there, which makes sense in their commercial point of view.
I think snapshots on ZFS are better than time machine though. Time machine is a bit of a clunky mess of soft links that can really go to shit on a minor corruption. Leaving you with an unrestorable backup and just some vague error messages.
I worked a lot with macs and I've had my share of bad backups when trying to fix people's problems. I've not seen ZFS fail like that. It's really solid and tends to indicate issues before they lead to bigger problems.
Shadow Protect by StorageCraft was brilliant. Pretty sure MS actually licensed Shadow Copy from them, but I could be mistaken. It's been a while since I played in that space.
Time Machine is good for the technically savvy, but for the non-tech-savvy, without something like the AirPort Time Capsule there's no real easy configuration for it.
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.
