Accusations can last forever even if they're thoroughly debunked, and they can be dominant in large part thanks to SEO and the spread of info online rather than anything the victim can control.
This is why the EU wants the "right to be forgotten" on Google etc - to let the innocent be innocent.
Denying the existence of provable facts? I have a hard time imagining how that could be effective without a PR team and a compelling narrative to be spun.
What does "proof" of your visiting a porn site look like, when bad actors set out to discredit you? I weakly agree with your second sentence, but I am not sure I understand the first.
Anything that would be claimed as proof could just as well be a collection of manufactured lies rather than leaked truth.