The web has grown quite a bit over the last decade, and WordPress has fallen behind ever so slightly. More applications are being brought to the web with JavaScript and more dynamic websites are being built with languages like Python and Ruby.

WordPress core and even a few professional WordPress developers feel that WordPress’ heavy reliance on PHP and minimal use of
JavaScript has become far too outdated. This is something the WordPress REST API is meant to solve.

This doesn’t mean WordPress is moving away from PHP, but it does mean developers should consider learning JavaScript if they want to take advantage of what this API has to offer.