Re: That probably explains..
I am sure that when the focus groups were asked What do you want most in a smartphone?", they all replied "A very thin phone" -NOT! Actually most iPhones from the 6 onwards are not actually 7mm, but something like 15 or 20mm, because if you want the thing to run for for a business day (that's about 10-12 hours) you will need an external battery case which more than doubles the thickness (and adds several layers).
And don't forget the "wet bar of soap" finish, which virtually guarantees the thing gets dropped regularly - unless you put a case on it.
A decent iPhone would be something like 12mm thick with a decent, non-slippery, scratch resistant finish. The battery would last something like 36 hours with reasonable use.