Is OpenAPI Still Relevant When You Tell Claude "Make Me an API"?

I hear a version of this question constantly now, and it is usually asked with a little smirk: if I can just tell Claude “make me an API” and it does, why do I still need OpenAPI? Why do I need AsyncAPI, JSON Schema, Arazzo, overlays, Spectral, all the machine-readable ceremony, when the model can conjure the whole thing from a sentence? It is a fair question and the answer is not nostalgia.