@sjw You only have one namespace.
JSON formats are cathedral style by essense, only one entity can say if you can use something or not. Meanwhile XML doesn’t gives a damn if you shove another namespace (which can be your own) inside of it. That’s an inheritance from SGML btw and it allowed for HTML5 to effectively be able to add new elements without every non-up-to-date browser potentially choking on it or failing to fallback to older style elements.
Like roughly <video src="https://example.org/video.mp4"><object src="https://example.org/video.mp4"><a href="https://example.org/video.mp4">video.mp4</a></object></video> can’t be done in JSON, while that would work from the first web browser to the very latest with probably okay compatibility for Mozilla 1.0.
@lanodan @sjw Building an SMS gateway doesn't seem that hard though.
https://www.appservgrid.com/paw92/index.php/2019/03/29/4-best-open-source-bulk-sms-gateway-software/