It has extensibility by having `'{' blargh '}'` be "don't parse the content between the braces". That isn't meaningfully different from just using strings/CDATA in json/xml.

The `blargh` between braces also can't contain closing braces - so they're not even fully generic.

Also, personal pet peeve - it should have a way to specify floating point values in binary, as there are many floating point values with textual representations that are massive and/or don't have numeric representation (nan, infinity, signaling variants)