The combination of screen size, resolution, and non-broken browser to render non-mobile-specific websites tolerably.
That's how it broke the “smartphones are niche because the mobile web sucks, and the mobile web sucks because there are so few users that its not worth improving” barrier.
Don’t forget Apply also got the soft keyboard right which was no small feat. People were dead set against it but here we are no physical keyboards anywhere on smartphones.
Sure. Not sure that was indepedently important (for adoption, it clearly had a big impact on the course of mobile interaction) but even if it wasn’t it was essential to the web thing, because otherwise you couldn’t have a usable keyboard and a sufficiently large screen.
That's how it broke the “smartphones are niche because the mobile web sucks, and the mobile web sucks because there are so few users that its not worth improving” barrier.