Not at all. You are using an example with hundreds of years between it's creation and now. Over that time it has become an example of culture. In the context of art, culture is a degree of sophistication, an example of a learning or method. Those statues very much meet that criteria now. P.T does not, how can it?
And the people that built those statues very much matter, because they have every right to determine what is and is not done with them. That they are not around anymore is a convenience to your point, rather than an irrelevance, because you get to use owner instead. The creator of P.T is around, and calling the shots with what happens to something you personally consider culturally relevant. Fortunately neither of us get to make that call, but common sense tells me P.T offers nothing of cultural relevance to our generation or species or hobby that other examples do not, and that in 5 years 99.9% of the planet will never of even heard about it, let alone have any idea what it is, if that even is not already the case, which it likely is.
You can't play keeps with every single little thing and say 'but culture' because it's pointless when far more relevant examples exist. It is shit how this has played out, but your position is weird.