[rswail]

This "stuff" allows for easy exchange of API definitions and Arazzo goes to the next level to define the semantics of the process of combining API calls.

gRPC requires brittle compilation of the protobuf definitions that has impacted every marshalling/serialization protocol for remote procedure calls since XDR.

Whether you like it or not, HTTP/JSON are the lingua franca of the internet (at least the API side of things). Protobuf is good if you are in control of both sides of the API, less so if you are just the server. It also is much less self-documenting than JSON Schema/OpenAPI.