Drupal has one of biggest and more active communities across FOSS, maintaining a large and vibrant ecosystem of extensions and installation profiles. The large community makes it easy to get help when needed.
Drupal is not easy to get into and out of the box doesn't offer much. To get Drupal doing what you want it to, modules are required. To get modules, an understanding of how Drupal works is required. And that takes time.
Admin interface is constantly being iterated on to remove unnecessary legacy features and to streamline the interface. Resulting in a very clean and easy to understand interface that also offers a wide range of options.