It lets you use stripe.js (thus getting the PCI compliance benefits) without Stripe being able to spy on your visitors.
> Why should I trust you?
> [...] If you're worried about both, consider this a proof-of-concept which you should replicate on your own server (using a separate domain name from the rest of your site).
Do NOT use an unknown third-party, without PCI qualification, to whom you have no contractual relationship, in between you and your payment provider.
Seems fairly "disclaimed" to me.