First off, if it's overwhelming or if it goes overboard, people just won't use it, so your example of advertisements on every surface and excessive tracking of what users are looking at and doing at all times will likely either not happen or occur but never be demonstrated in any practicable, user-facing way.

Second, even with Facebook owning Oculus and investing heavily into its success (rightly so, by the way, the Oculus hardware is phenomenal), they're only successful because other software developers have made such great use of their systems. In some cases, Facebook has bought the successful software/companies involves (Beat Saber...), but it'll take a long time before they establish both a top-tier VR hardware and software footholds.