Json doesn't support comments specifically to not allow parsing directives, that means less customization. More customization of interoperability protocols is not always a good thing.

The compiler I [occasionally] work on does not abuse comments for directives. All directives in that compiler are out of band.

No, but it is an argument against "ASN.1 is superior to protobufs".

Many modern high-volume telemetry systems use gRPC for a good reason, it wins in the "pragmatic" department.