Consumers flocked to the iPhone because it was designed and targeted to everyone and not just business users like most smartphones. The App Store wasn’t even part the early story. Early on the killer apps were first-party. One device that could call, text, provide GPS, act as your iPod, and had a real internet browser? That was insanely desirable. The App Store didn’t even come out until after the iPhone was already a market success. The App Store and devs arriving to it is what allowed Apple to kill off most of the rest of their competitors, as software markets will not support fragmentation.