Because YAML, as much as it sucks, is relatively straightforward to write by humans. It sucks to read and parse, you can make tons of small mistakes that screw

Because YAML, as much as it sucks, is relatively straightforward to write by humans. It sucks to read and parse, you can make tons of small mistakes that screw it up entirely, but it's still less cruft than tons of needless "": { } . For short configs, YAML is acceptable-ish. For anything longer I'd take TOML or something else.