Drupal and WordPress are similar, but different, pieces of software you use to power your website. We used to build sites with both, but lately our focus has been exclusively on WordPress.
Perhaps surprisingly, one of the biggest reasons is the pace at which the software is developed.
Average time between major Drupal revisions: 2 to 3 years.
Average time between major WordPress revisions: 2 to 3 times per year.
Degree of change between Drupal revisions: large changes, breaks compatibility.
Degree of change between WordPress revisions: small changes, rarely breaks much.
Cost of moving from one Drupal version to the next: very expensive and time-consuming.
Cost of moving from one WordPress version to the next: simple, often trivial.
When you see this pattern emerge, and you care about supporting your clients moving forward, it becomes difficult for a web designer to recommend Drupal without a very good reason.