Well once you log into it with you FB account you also might have signed a (likely illegal) TOS/AGB which allows them just that under some esoteric reason like

Well once you log into it with you FB account you also might have signed a (likely illegal) TOS/AGB which allows them just that under some esoteric reason like giving you the more person specific advertisement you want by including all you Oculus interactions. Also don't forget that there is quite a social factor to VR and they are pretty much going in the "single player only usage without FB account direction".