"pinch to zoom" is obvious. It's practically the only way you could zoom things on a touch screen.

It's like patenting the steering wheel.

Don't pretend it's innovative or took any time whatsoever to come up with.

It's blatantly obvious and should never have been granted.

If it's obvious, why didn't it exist on any of the touchscreen products which went before the iPhone?

How many of those touchscreens could detect multiple touches at once? That's a prerequisite for doing pinch-to-zoom with a capacitive touchscreen.

It likely existed on the first light-pen devices from the 80s. Apple just happened to popularize it.