[xwowsersx]

I don't think OP's question is the same as the one asked about Dropbox. The Dropbox question was about why the service was needed at all when you could use Unix tools like rsync to achieve the same thing. The answer to that was simple: not everyone is a tech-savvy user who wants to mess with command lines. On the other hand, OP's question was about whether there's already a mainstream database and extension that does what Roe AI does. They got a response, and it was helpful. The "You can do this with rsync!" argument became a meme, but now it's almost overshadowed by the knee-jerk "That's what they said about Dropbox!" response.