100% correct. There is no way they included a depth sensor in this device just to blur the background. They may also be aiming to map any Amazon clothing purchases to 3D body shapes for a purely data driven approach to clothing recommendation to start with (as opposed to having 3D scans of every bit of clothing to do geometric fitting, which is prohibitively labor intensive.) So they'll know your shape, what exact items you've purchased, how often you wear those purchases, and (if I understood correctly) how your friends think you look in them.