And the amount of fine-tuning done on ios for the various gestures is quite astounding. Re-creating them using browser APIs isn't really entire possible.
You can extremely close if not imperceptibly there for a lot of interactions. The bigger issue is actually mobile browser “chrome” getting in the way (i.e. baked in gestures in mobile browsers)
It's one of those things that I love the idea of doing. I'd love to create my own look and feel and design.
But day to day at my job I just need a dang button that does the thing or transition between things, a spinner or ... whatever.