Nope, wrong again - you really should read up for an hour or two before responding. The lighthouse sensors are used as virtual space delimiters, which allows fictional reality to respond to the real-world space in which you are moving. They are effectively the same as AR markers. In fact, Valve used AR markers for a long time before perfecting the lighthouse concept! Fictional objects can even be displayed in their place, which many experiences do presently.

VR and AR are two names for the same thing. They're arbitrary distinctions that were made before we understood what we were doing. Eventually, these terms will stop being used entirely, or possibly, VR will be used exclusively.