Wrong. CSV is horrible to parse with its string quoting rules. JSON accepts only utf8 and is not misleaded by \, nor ",". Done both, JSON is much simpler and can represent nested structures, arrays or maps. CSV importers are mostly broken, and should be left to Excel folks only.
> It's that application logic shouldn't be operating on transport data formats
Nobody is talking about application logic here but you. JSON is one of the best transport data formats, and this library makes it much easier to encode/decode from/to JSON and C++.
We are not talking about javascript's hack to prefer JSON over full objects. Of course is an internal representation always better than an external, esp. such a simplified one. But for transports simple ones are preferred over complicated serialized ones, because then you can easily do MITM stack-overflows or abusing side effects on creating arbitrary objects.