Its similar in principal, but it also creates a signed version of the stripe response [1], so you can hand it off to a backend and validate it without an additional stripe call.
Instead of requiring users to input auth keys, it uses stripe connect [2] to securely authenticate and act on behalf of users.
Using Stripe Connect is something we are going to add.
I saw the need when I had a couple of simple apps where I didn't really have a web server where I could create payments/subscriptions via stripe's server-side libraries. I also didn't want to use stripe's Checkout. I had to spin up a simple service just to confirm the payments and I figured I could abstract it.
The signed jwt response can be helpful because now you just need paysly on the frontend and your backend can be dependency free - all it needs to do is parse the token.