Sadly they cut off my iPhone 7 and 8 and the X.
Remember the iPhone 4S? You could install iOS 9 if you wanted to, knowing that it would slow it down. Those who accidentally did were allowed to downgrade back to iOS 8.4.1.
This needs to be offered to older device in order to run newer apps or websites.
If I recall correctly you weren't able to freely install an older iOS on the 4S in any official way until years after iOS 9 came out and they randomly started signing iOS 6 (which can OTA update to 8.4.1). It wasn't something that was always an option.I know people that would have liked to downgrade but didn’t. Either because they couldn’t or because they didn’t know they could.
Up until now I didn’t know you could either.