It's so textbook that Google two weeks ago came out with their own competing "open" standard for doing the same thing!
You need some amount of strictness in the API here, LLMs are not actually sentient. You could say that this is a failure on OpenAI's part in comparison to their marketing, sure.
Consumers will only use the UI if it's better. Merchants will plug into the UI to make more money. So everyone wins-- consumers, merchants, OpenAI, and Stripe. And since the protocol is open, other chatbots and other payment processors can implement it too. Who loses?
(I agree that at scale these things tend to accrue to top players and you get all kinds of weird unsavory consequences. But I'd argue that's a critique of our regulatory apparatus, not of the companies building products and services.)
Nope youre not an idiot, I agree with your thoughts.