Earlier quoted context omitted.
The problem with XML is precisely that it is so much more than simple hierarchical, nested trees of data. The fact that in a casual conversation XML is reduced to hierarchical trees of data pretending the rest of XML does not exist more than proves OP's point.
I'm not pretending anything and I hate XML. I would still rather use it than HL7, because it's a hierarchical tree of data and HL7 is not. OP's point is that almost nobody wants to use XML anymore; my point is that almost nobody wants a Ford Model T as their daily driver anymore either, and yet it was still the future, in a certain sense.
It feels like a cross between JSON and HL7 to me.