> With JSON, you often send ambiguous or non-guaranteed data. You may encounter a missing field, an incorrect type, a typo in a key, or simply an undocumented structure. With Protobuf, that’s impossible. Everything starts with a .proto file that defines the structure of messages precisely.

This deeply misunderstands the philosophy of Protobuf. proto3 doesn't even support required fields. https://protobuf.dev/best-practices/dos-donts/

> Never add a required field, instead add `// required` to document the API contract. Required fields are considered harmful by so many they were removed from proto3 completely.

Protobuf clients need to be written defensively, just like JSON API clients.

It’s also conflating the serialization format with contracts