>>285612518
I don't understand why it's difficult but I've seen people everywhere use it wrong. If it was like the AR/VR/MR/XR terminology that's all goofed up I'd understand but outside looking in and inside looking out. Seems pretty obvious that it's about what's doing the sensing. 
Having to set up extra peripherals is a different thing entirely. Even in the beginning of the camera based tracking they were setting up Aruco markers around the room. Then with SLAM you still need to have enough features set up in the room for it to work. In a sense it's like the existing furnishings are the required peripherals.