tldr: Simplicity and utility trump large corporate backing.
In the middle of 2000, SOAP - an XML-based messaging protocol - started to rise in popularity as a communication protocol for distributed computing. By 2004, there were dozens of SOAP implementations in as many languages, including all of the most popular ones, such as Java, C/C++, .NET, Perl, and PHP. The term Web service became popular, describing a new model of interaction: APIs over the Web.
I was on the team that shipped various SOAP and Web services products at Microsoft. This included various product management tasks, designing features, working across companies on interoperability testing, chairing the first WS-I committee, etc. I helped build and popularize SOAP. And I watched as it lost.
Ten years later SOAP is gone. Very few, if any, developers, are creating new SOAP-based Web services. But Web services, APIs over...