You clearly didn't understand how the path element in SVG works. The M, L and other characters contains valuable information. M stand for move, L for trace a line, but you can also have instructions for bezier curve or Z for closing a path. Your json format by removing this information is useless.
- anything as long as there's a way to stream the data (which is not possible with your format as you need to receive the whole object before being able to do anything).
this makes me realize that xml maps relatively well to JSON array whose elements are object with 1 fields (or 2 fields) whose value is again a similar array.