"For files that changed or were deleted: move them into a new delta folder. For new/changed files: copy them into the latest snapshot folder." is just redneck copy-on-write. It's the same result but less efficient under the hood.
I mean the idea sounds cool but what are you missing? ZFS even works on Windows these days and with tools like zrepl you can configure time based snapshotting, auto-sync and auto-cleanup