There’s a nice rebuttal from one of the ntp people in the article’s comments.

JSON is a disaster for many reasons. Hardware incompatible floating point is one; inconsistency in parser implementations (and ambiguities in the spec) also don’t help.

Also, why use a tree structured data representation when the underlying data structure is fundamentally just a N-tuple with a fixed schema?

Similarly, why use a text protocol to send around fixed length blobs or encrypted data?