JSON came along and wiped out XML for web apps (but did you ever wonder why we fetch JSON using an XMLHttpRequest?).
XML didn’t live up to expectations, but spending a lot of money on interoperability kinda did. Supply chains are a lot more integrated than they used to be. Financial systems actually do send financial data back and forth. RPCs really do get Remotely Called. All that stuff got built during the XML craze.
XML, the data format, didn’t have much to do with it. We could have just as easily exchanged data with JSON (if it had existed) or CSV or protobufs or whatever. But XML, the dream, was a fad everyone could get behind.
A quick, interesting read and some predictions for the future.