Anybody who thinks that you can just chuck unstructured data into LLM and YOLO the app is an idiot.
This works up to a point, and then it doesn't. And you're left with tons of inconsistently formatted data.
My company is built on protobufs from ground up :) We use it in the database, for remote calls, on the frontend, etc. The protobuf language is not great, but it's about the right balance between too expressive and too restricting.
And the best thing is that it's compact, compared to OpenAPI.