Making Drupal into a technological marvel has cost it losing the lower segment of community, it's "soft underbelly", and Drupal has steadily been bleeding market share ever since. That is why WordPress is growing in market share, and Drupal is dropping. Here's why.
There are 3 aspects that make Drupal 8 more robust than WordPress code-wise: selective loading, quality, and caching. Generally the object-oriented code (OOP) is slower than the functional code, and having more code is slower than having less code. Drupal 8 has way more code than WordPress and it's OOP. So why did Drupal 8 beat WordPress by average 20% during my tests? Here's why.
Some CMS are like Duplo - very easy but very limiting. Others are very flexible but you need to code a lot. Drupal is the golden middle.