There is an implicit understanding with the Pittsburgh Steelers that the defense is the priority side of the ball; that history shows teams have had their most success when they are strong on the defensive side of the ball. So when the defense fell apart shortly after the 2010 season, it’s not much of a surprise that they spent so much trying to build it back up.
From 2013 through 2020, for example, they invested every one of their first-round draft picks on a defensive player, including their 2020 selection, which they traded away in order to acquire safety Minkah Fitzpatrick.