No. Gumroad hosts and sells digital products from a store.

This site...well, I can't even tell what it does aside from creating a paywall link that requires $X to bypass. And on that payment page there's no hint as to what you're buying.

And after you've gotten a new link...then what? Someone can just post that link everywhere? Or is there some kind of API that unlocks a link? Or...?

The service has very questionable usability. Gumroad has obvious utility. That's the difference.