Nonlinear narratives are so popular in the 21st century because there are endless amounts of things you can do with nonlinear narratives because the don't follow a linear path and they can circle back to any previous moment in a story. The different options in a nonlinear narrative are what makes them so popular. You can play or read the story many times and do different things every time. For example when we played the Walking Dead game we could choose different options and have different outcomes. Nonlinear narratives can easily incorporate any idea that comes to mind unlike a linear narrative that has to follow the same plot throughout the whole story.