> And how can JSON not count? If something does not have drivers for its success, surely it would not have succeeded? 

I think JSON succeeded because it was already existing and got discovered so it was free and already had traction and some sanction as part of _javascript_. So it did not need the ingredients to success that a new technology would need. It did not need a vacuum to fill, developer adoption, new parsers, bug fixing, security patching and rethinks, lengthy specs, standardisation, expensive consultants, evangelists. These were hurdles XML had to overcome and a new technology would have to overcome.