I guess my point was that I'm rather on the side of "Ok then maybe it is still worth finding a serialization format that maps better to my domain, like perhaps that can serialize numbers with the same precision without having to route them through a string and back." This is like claiming that it's not worth comparing programming languages because machine code is Turing complete.
There is absolutely nothing inherent to JSON that would cause the woes the author is experiencing.
Any data can be serialized with JSON.