I don't think I'd agree that it's a problem with the tool. However you do raise a good point - that there are problems that JSON and similar struggle with where XML would introduce a noticeable amount of unneeded complexity. It's a wide enough gap that a simplified subset of XML is probably be warranted. (I assume it must exist by now and I've just never heard of it?)
> a simplified subset of XML is probably be warranted
There are several. And that's the problem. It isn't hard to find a subset with a library for a single language that uses a slightly different subset from the other subsets. But none of them ever caught on.
