Factory Reset does not mean to reset the phone back to the original version it came with. Factory Reset is basically erase everything and load the protected partition to "reinstall" the OS (if you upgrade your OS several times, it will use the current OS version.)
Factory Reset term been around for so long and everyone already know the term meaning. Even I remember that term 25 years ago. Apple chose to change the language and this cause confusion. "Factory Reset" and "Erase all content and settings" didn't implies the same meaning. Apple should add a subtitle or a tooltip to indicate that it is factory reset or additional context for us to understand what it does. So why change the term if it isn't broken?
Factory Reset term been around for so long and everyone already know the term meaning. Even I remember that term 25 years ago. Apple chose to change the language and this cause confusion. "Factory Reset" and "Erase all content and settings" didn't implies the same meaning. Apple should add a subtitle or a tooltip to indicate that it is factory reset or additional context for us to understand what it does. So why change the term if it isn't broken?