There are other things that make JSON a bad configuration language with poor human readability and writability. Lack of multi-line strings is a big one. The requirement to put a comma after every array item and object member except the last has made me write more syntax errors in JSON than I've ever written in YAML. Also, JSON is unsuitable for config files with lots of Windows-format paths, since backslash is its escape character.

He didn't "refuse to add" them. JSON had comments, and then he removed them.

YAML works better with line-oriented diff'ing systems - i.e. git (though you need to massage it a lot to make it sensible).

Json is a fragment of yaml, which means that all valid json documents are valid yaml documents.

Yaml has parts that broaden its use cases, but I'm slightly surprised that json+yaml comments isn't a more widespread thing.

TOML is actually pleasant to use for like 99% of use cases honestly.