[adamstep]

Author here. The meta-point of my post is that different formats have their advantages and disadvantages, and it's good to understand those when deciding on what's appropriate for a given use case. So I'm glad to see a discussion weighing the pros and cons in the thread!

I see some comments saying that JSON can represent trees just as well as XML, which is technically true. However, XML natively supports a distinction between node metadata (via properties) and relationships (via child elements) that has to be implied in JSON. For pure-data, this may not matter . But in cases like UI layouts, it's helpful to have the format distinguish between node properties and child components. As others have mentioned, the document use case is also a natural fit for XML by clearly separating the content from markup.