> XML-DSig isn't great with XPaths

Or at all.

> How would you digitally sign a Json document and embed the signature in the document?

Preferrably you wouldn't because that's a really bad idea.

That said, this type of support-every-conceivable-idea design-by-committee systems would be equally bad built on json or anything else. That much is true.

There's probably no silver bullet here. But that is still not an excuse for XML-Sig.