Many people have taken the view that "oh, it's on the cloud, I don't need to back up any more". I view this as in every way wrong. I'd take the view that nothing with automatic 2-way sync can possibly be a backup. Mistakes and the consequences of failures are soon in both places (or neither). That said, the Creative Cloud syncing seems to be lazy, and that might be a saving grace in some cases. It also, to my mind, magnifies the chance of losing local files.