Okay, I have teenagers. They are very aware that large amounts of illegal, often pirated, email is available on the Internet.
If I search for online movies, the first two pages of results are illegal sites. Yet DS went to university and managed to sign up for a streaming service rather than watch illegal sites.
DD came home from school and told me about a lesson they had in IT on piracy and illegal Internet content.
So I would expect it to be common knowledge among teenagers that hub sites, regardless of whether or not they are pornographic in nature are full of illegal content. I would expect people to know that such content will include material that would not pass censorship laws and film classification in the UK.
I would not expect my teens to browse illegal material because they couldn't be arsed to find a streaming site that was legal, or believe that people who had signed up for Netflix were connoiseurs of cinema!
Behaving ethically online isn't some extra effort. Ethics are something you already do everyday offline and just naturally do online. I don't receive stolen goods in real life, so I don't do it online. I wouldn't enter into a sexual situation with someone offline without making some attempt to find out about them, their age, their general wellbeing, so I don't do that online with porn performers. Clearly very many other people take that approach or social media would not be one of the main referral mechanisms for porn.
If the majority of people chose to access mainstream cinema through hubs, film classification and censorship would simply collapse, because people would be viewing material outside of the law. The same is true of porn. To enforce whatever porn laws are advocated, you need the government to enforce it by going after illegal porn, and you need the porn watching public to say they can be arsed to stick to legal sites.