If Google was still concerning itself with representing the content of the internet, this would be the case, but increasingly Google is tailoring its results for whatever other varied ends.
If it is curating the data, then how it curates matters. In this case, they've curated most of the porn from the first page of results, from the looks of it.
But Google has agency to adapt to the content if needed. If black-hat SEO gets the upper hand and results in an Internet trending toward cheap/fake linkbait, Google (or any competitor) doesn't have to just shrug and give the excuse, "Our shitty search results only reflect the shitty Internet"
