You know, I'm not entirely sure it's a bubble thing really. PT was really really big because of the intense quick word of mouth it got and then the explosion of actually being a Teaser for Silent Hills. But shit like Lisa and the baby and the weirdness of the game was def something that helped it being a hip thing for the moments it wasn't a teaser. It had that "it" factor that some games have from time to time.
The cancellation of the project only cemented the fact that people that wasn't into these genres could be interested in experiences like these. PT helped the genre a lot to cross from a subgenre and bringing new people. I do agree that the fact that it tried to hide under the box of an already popular genre (ah, get it?) shows that it was a big genre from before. But I think that even being big, it became bigger or more "mainstream" (god I hate that word) with PT and it's cancellation.
So when referring to it being a bubble thing, I'm talking less about the flash hype of "omfg! It was really Silent Hills! By Kojima! With Del Toro!!" and more the kinda talk that we're actually having as a topic of this thread where the implications of a longer term impact is being discussed.
I already acknowledge that there definitely was a lot of hype and coverage about PT turning out to be Silent Hills. But attributing the fact that many people got excited over what was effectively a teaser for a new entry into what actually is a truly influential classic horror IP isn't the same thing as that interactive teaser itself changing the future landscape of the genre much.
The bubble aspect is where members of a community such as this can often pay little to no attention to subgenres that are plenty healthy and thriving, until something comes along which places it on their radar for a different reason (Sony + Kojima + Del Toro, for example). So now,
because this type of game is suddenly on their radar, anything that comes after it is attributed to having been influenced by the first thing they actually paid attention to the existence of, regardless of how many prior notable examples exist. OP already started implying the Resident Evil 7 adopted a first person viewpoint as a result of PT, despite interviews existing that prove this not to be the case at all. Someone who paid attention to the subgenre prior to PT's reveal, and saw titles like Amnesia, Condemned, Outlast, etc all finding success for themselves, would likely be a whole lot less likely to see Resident Evil 7 and attribute it's existence to PT specifically. And you know one of the main types of people that are likely to have actually paid attention to a subgenre and be well aware of prior examples within it? The people that create such games.