I bit of anger or at least disappointment in your post. However, "The fact that everyone has a device with a bunch of proprietary backdoors that they don't have root on and that serves as a single lynchpin through which their life can be ruined is the most fundamental destruction of personal computer and identity security that's ever been realized" is completely true.
It all happens in the bacground. You define which folders to sync and additionally you can sync with as many devices you wish (e.g. a backup in your own server).