Nobody had even thought of it before the advent of the smartphone. Steve Jobs has a lot to answer for!
“Smartphones” existed some time before Apple got in on the act, have you not heard of Blackberry or Palm?
All Apple did was make them simple to use for anyone, without needing a stupid, easily lost stylus, and call it an iPhone, instead of a PDA, like everyone else, e very astute bit of marketing.
I had a Nokia N95, had a 5Mp camera, GPS, etc. It was utter crap! Nothing worked properly on it, then the iP3G arrived…