In its heyday, the blackberry too was seen as the gold standard of smartphones, and people simply couldn't imagine a better way of making a smartphone.
I hate this myth. On the contrary, alternative methods were constantly being explored.
The Blackberry was seen as a business standard, but it was just one style type. Touchscreen phones were also popular and getting more sophisticated.
Heck, the very FIRST smartphone back in 1994 was all-touch and could run third party apps. Later all-touch smartphones included swipe gestures and orientation sensors:
By 2006, it was widely predicted that capacitive all-touch smartphones would soon become popular.
In fact, months
before the iPhone was shown off, a free Linux group had announced plans to build a developer's smartphone with multi-touch and pinch zoom. Some people even think Apple stole their idea (I don't):
It was all leading up to a similar slab style, and a switchover to more touch friendly UIs:
Apple's primary advantage was that... unlike major manufacturers of the time... they did not have years' worth of legacy smartphones to support. (Of course, later on, they did, and that's why it took a while to see larger iPhones.) So they were able to burst on the scene with a fresh start.
(Of course, Apple couldn't have done that without the billions of dollars and years of R&D and infrastructure building that all the other manufacturers had committed long before.)