Not to vouch for having Git store things in human format. But I often think about how inefficient JSON API's and YAML storage formats are (in parse time) just to be a benefit of a user debugging it or discovering the API through a browser. But since most people use a JSON prettifier plugin or a tool like Postman anyways, what is the benefit of the line format being character strings? Wouldn't a binary package not be just as easy translatable into human readable JSON formatted output as a compacted JSON string is?
One benefit is that I can look at an arbitrary file/response and be able to tell with a fairly high certainty whether it's JSON, YAML, or TOML, but there's no way that I tell whether it's messagepack, bson, or protobufs.
But I think you should be able to detect the type of format for binary encodings just as well as there spec is pretty specific. Maybe not at glance as a human, but that is the point I'm making. Should all line formats be made absolute human readable and parsable at glance just to the benefit of debugging at the cost of performance. Where with just a simple lens tool you can look at the data in a completely different (human friendly) view. Tools like this already exist in the form of WireShark, only they mostly operate at a deeper level.