The counterpoint here is that a lot of the success of JSON was in presenting an alternative to the then-state-of-the-art, which was basically "here's a small mountain of spec documents explaining how you need at least fifty megabytes of metadata spread out over forty-three separate namespaces' worth of elements to safely send a single string key to someone else with XML".

And at the time people insisted JSON could never replace that, because JSON was so underspecified and unsafe. You could maybe get away with it for a couple requests to your puny baby child's "Fisher-Price My First Webservice" toy program, but JSON would instantly and completely fall over the instant any real-world problem presented itself.

Yet here we are all those years later, in a world which largely runs on JSON as a data interchange format.

Or, more concisely, as I wrote in 2006 in response to the Dave Winer piece someone else linked in another comment:

And now here are these kids with their startup companies and their weblogs who are getting data exchange and even things that kind of look like APIs out of… JavaScript arrays? The XML guys are sitting up on the mountaintop like the Grinch, with his pile of stolen presents, wondering how Christmas still managed to happen: it came without specs! It came without hype! It came without angle brackets, envelopes or types!