What kind of plug do you find in cars? What kind of plug do you find in hotel nightstands? What kind of plug do you find in airplanes? What kind of plug do you find in almost every outlet charger made by Apple or anyone else? The answer to all of those isn't USB-C. So if you want to connect your iPhone to both your laptop and almost all charging sources in the real world, you need either two cables or one cable and a dongle.