I think nom-nom is trying to imply that if you're passing GBs of Json around, "human readability" isn't probably a concern. Therefore you could go for an efficient binary format.
JSON isn't just about human readability, it's about being a 'good enough' standard for data exchange. What binary format would you use that people could parse as reliably as JSON?
In case your question wasn't rhetorical, I believe MessagePack is the leading schema-less binary serialization format (which does not contradict your point as it is still less ubiquitous than JSON).
