When the iPhone is disabled, the device recommends the users to connect their device to iTunes to get access. While most of the users can do it easily, others have trouble connecting to iTunes. This happens with the users who are connecting their iPhone with iTunes for the first time. As the first time connection requires authorization, the connection fails.
So, when a user complains that- my iPhone 7 is disabled and won't connect to iTunes, it's because you have never used iTunes before with that particular device.