That's true! OpenAI would/could lie. Even so, a signature would solve a lot of problems: aggregators/resellers rewriting the {model: X, ...} in the payload, staged benchmarks (there's currently no way to prove a dataset's answers actually came from the model claimed), MITM... Of course, it's not that dire, and there's no incentive for OpenAI to look at it. But I was kinda shocked to find out there's no way to guarantee something this basic (though maybe it's not as simple as I think). Who knows? It could add a lot of latency. I'd rather think it's more a lack of will