I don't think I understand. Why would they go to the trouble to launch this API, make claims of being able to process payments, etc. if it is "useless"?
This API is designed for business payments. Companies that process tens, if not hundreds of thousands of payments on a monthly basis. Think about the companies that sit behind businesses like Etsy or Uber - they need to take a lot of payments from customers and pay the supplier.
Many of those payment companies are financial institutions themselves who probably already have some kind of connection to programs like Visa.
It's not useless if you have a merchant account.