Comment by SigmundA

>Right, both sort of suck at streaming, something about being closed form tree structures would be my guess(strictly speaking, you need to close the tree to serialize it, so no clean way to append data in real time, best you can do is to leave the structure open and send fragments).

Again don't really agree, its just most developers don't seem to understand the difference between a DOM or parsing JSON into a full object vs using a streaming reader or writer so they need to be hand fed a format that forces it on them such as line based CSV.

Maybe if JSON and XML allowed top level multiple documents / objects it would have helped like JSON lines.