Yeah it was in the first iPhone but you can't control the amount of zoom and it often guesses wrong or just doesn't work. I pretty much gave up on using it. On Android in most apps you can double tap, hold the second tap, then swipe up and down to zoom. It's a lot more natural than it sounds and it gives you precise control over both the zoom location and zoom amount.

On iOS you can try the gesture in Maps, and then wonder why they never added it to Safari.