Mobile apps has the feature to control what specific content you want delivered to customers where as on the other hand , it provides better user experience, The main purpose is to increase engagement and website conversion , making people to buy your stuff, especially if you run an ecommerce site. It’s just smart business to consider a mobile app for your website, as 83.72% of the world’s population owns a smartphone, and a lot of people are on the go, so more than likely, they are using their phone over tablet, laptop, or desktop PC.
Sure, you can forgo building a mobile app for your website, and solely rely on your WordPress theme’s responsive design, but unless you do a lot of customization, it will not perform as well as a mobile app.