json is fine as a serialization format for things that need to be text, but it's not great as something that gets edited by hand.

not that I enjoy xml, but writing long strings in json is even worse. xml I can write multiline strings as a first class entity.

I can add a comment to an xml document, json I have to write something hacky like "//": "my comment" and hope whatever is consuming it doesn't care.

there's just as many problems with json parsers, since most but not all of them treat numbers as js numbers, which are basically floats. you can't rely on an arbitrary consumer having support to parse ints above a certain size so you just have to make everything a string and hope.

json allows duplicate keys, but they get overridden by the last occurrence. you can't round trip json without losing something. you can't rely on just seeing a key value in json text and that being correct since there could be another later. doesn't come up often but it's there.

The entirety of the banking world uses XML very heavily, as it's part of the SWIFT standards.

Really? Right in front of my AJAX?