This is not a payments gateway. We use them for something entirely different than processing payments or credit cards. I haven't seen a general PCI-compliant transparent PII tokenizer proxy service like that. If you know of one, let me know, maybe we'll even switch. But this is not a payment gateway solution, and it's offering many more use cases than an iframe or credit cards.
There's already quite a few payment gateways where an e-commerce site can iFrame the payment page (or similar) to ensure that they never see the real cardholder data.
(the fact that this shouldn't really make them out-of-scope for PCI is a different problem)