If they're collecting money, be it W-2 or 1099, they have to disclose their real name and social security number as it is to whoever is paying them, for tax purposes. Generally to the studio hiring them, but if they publish directly to a monetized platform, they'd have to provide the same to the website as part of collecting their share of ad revenue. So there's really no excuse for PornHub not to either directly verify performers or verify that publishers have all of the performers credentials in order.

Beyond that, of course, it's important for adult actors to be able to be represented publicly solely by their stage name. PornHub knowing both actually adds an additional protective layer, as PornHub could filter/block appearances of their legal name.

I definitely agree the court system should uphold pseudonyms and anonymity when revealing their legal name in public records and hearings has the potential for significant harm, but that's a very different issue than the record-keeping that adult film producers are already required to do.