How do they reasonable work around that though? If they want the ability to move away from JSON, you have to know that it is JSON before trying to parse it. And then you need to know how much data to read. So I can see why they put those 2 tidbits of info above data block.

Maybe they could have said too bad, JSON for life, we'll never change it. OK. But then you still need the length or a delimiter for the "end of json".