In my experience SOAP was near-universally used as an RPC encoding, where the schema was whatever types the exposed API defined and no-one gave the tiniest anyt

In my experience SOAP was near-universally used as an RPC encoding, where the schema was whatever types the exposed API defined and no-one gave the tiniest anything about the data representation on the wire. If you insisted on schema first SOAP, people looked at you as if you had fallen through a dimensional gate from an alternative history parallel universe full of Zeppelins and domesticated dinosaurs. JSON on the other hand came riding on that REST wave, where the data models on the wire were given more consideration than just an outcome of the serializion process best never looked at. Some people even considered idempotency more than just a funny sequence of letters. No, I'm not surprised at all the SOAP mindset disappeared. (But SoapUI was really a pleasure to use, spent an ungodly amount of hours staring at that thing, never in anger)