Drupal is a CMS. One might even say that Drupal is a good CMS and they would be right about that, in my not-so-humble opinion. At its core, Drupal is able to define content really well. Sure, it needs to do better at making the content editor's experience pleasant, apart from other things. But defining content structures that are malleable to multiple surfaces has always been Drupal's strengths. This makes Drupal an excellent choice for building a Digital Experience Platform (DXP).