sync is something that is required when you have multiple master copies of something, whether it is a directory, a contact list, whatever. It is another kludge to workaround the fact that we are not yet in an online world, and it is still safer and easier to edit a local copy and then sync up to a remote master than it is to edit a remote master directly. I dream of a time when we have write access to the single remote master copy when we need it, then sync isn't necessary.