What was the advantage to me as a consumer if a 2015 iPhone got USB-C? IMO, USB-C wasn’t an advantage over Lightning then. (USB-C was not yet a common connector and most Apple users already had Lightning cables or could get by with the one included with the phone. Apple users had 3 years of orientation-independent convenience before USB-C arrived.)
I still find plugging in the Lightning cable to be easier (less precise alignment needed) than a USB-C and by the time the iPhone 8 arrived with magnetic charging, any charging advantage to USB-C went away.
