Then why hasn't anyone else done it before?

With hindsight, it's always easy to say anyone could have done it too, but there's more to product success than just coding and shipping an app out the door.

The first iPhone was built using COTS(commercial off the shelf) parts that Nokia, Ericsson and Motorola also had access to, and SW tools they also had access to, yet Apple won and buried the other companies. I'm sure engineers from Nokia, Ericsson and Motorola also said "we could have done exactly the same thing with the right leadership".

I also say "I could have done that" when I see how the maker of Flappy Bird became a millionaire or any other top 100 AppStore slop app has 100+ million downloads.

Coding skills are dime a dozen these days. A lot of people can do 95% of the same things. The differentiator comes with the 5% rest.