What is XML?
Verbose, strict, and still holding up enormous amounts of the world - government feeds, financial messaging, publishing, office documents. JSON took the web from it, but anywhere with schemas and validators and twenty years of history, XML is what's on the wire.
What is SQL?
Not a file format so much as a language, but a file of INSERT statements is how data has always been moved into a database. Every engine will run one, and it's the least surprising thing to hand to a database that already exists.