Because the devices involved are mobiles? What else would you use.

Almost all end–user devices are mobiles. When everyone had a desktop you made a desktop app. When everyone has a mobile you use a mobile app. When everyone has brain implants you'll make a brain implant app.

That's if you want to reach the most people. If you want to reach the much smaller community of people who oppose the current thing, you'll make a different type of app.