@BlueLiquidDesigns @chrisburgess I agree that JSON APIs are superseding XML APIs everywhere. But there are still a lot of WordPress clients which are using XML-RPC protocol…such as WordPress Mobile App. WordPress is still adding new XML-RPC functions and working on its improvement. So its not outdated rather is under continuous development.
XML-RPC wasn’t covered here so we wanted to document it here. There is nothing wrong in learning both XML-RPC and JSON REST API. For some non JavaScript programmers XML seems to be more suitable.
Thanks.