What flat surface do you close by pinching it? Moreover, it seems you're trying to equate "intuitive gesture" with gestures people use with (non-computer) every

What flat surface do you close by pinching it? Moreover, it seems you're trying to equate "intuitive gesture" with gestures people use with (non-computer) everyday objects, but I don't see why that is a requirement for intuitiveness. Pinching to zoom in and out makes a lot of sense in my mind. Place your thumb and index finger at two points on a map/image/website. Those two points are two corners of a visual area. To make that visual area larger, expand the points outward. To make the area smaller, pinch inward. This conceptual mapping is very straightforward.