And you are absolutely responsible for ensuring that the porn you watch is adult and consensual.
Well... no. But even if viewers were, how do you go about ensuring that it's abuse free? It's not like you can just google the production company. There are plenty of times where there aren't any publicly available allegations so you can never be sure. When it comes to amateur porn, how do you know if their partner is forcing them into it or not? There's no way to prove anything for sure unless there is a public record of allegations.
You do understand that abusers can lie about what they're doing, right? And that victims of abuse will often not come out in fear of retaliation from the abuser. You're saying that the viewer should be required to prove that something doesn't exist. It's an impossible task.