Why not HOCON?

HOCON is another "redesigned" JSON, ironically enough, taking JSON and making it even more complicated.

Along with JSON's syntax typing - a downside of most non-YAML alternatives, HOCON makes the following mistakes in its design:

• It does not fail loudly on duplicate keys.
• It has a confusing rules for deciding on concatenations and substitutions.
• It has a mechanism for substitutions similar to YAML's node anchor feature - which, unless used extremely sparingly, can create confusing markup that, ironically, is not human optimized.

In addition, its attempt at using "less pedantic" syntax creates a system of rules which makes the behavior of the parser much less obvious and edge cases more frequent.