Every single major operating system ships with WebDAV remote filesystem support built in and it works reasonably. Subversion is built out of WebDAV and can be wired to naively auto-commit changes these clients store.

Maybe it's on the decline, but I'd hardly put it as something that "never really found its footing". It is still a decent way to do fileshares over the public internet without sshfs, etc.

That's not really what the link is, though. It's an adaptation layer to turn a random network resource into something that looks like a filesystem.