[banachtarski]

The designer evidently hasn't looked into any of the multitouch research. This interface would actually be far harder to use, learn, and get accustomed to than existing interfaces. It's unintuitive. There's no reason why 2 fingers should correspond to volume. With loose coupling like that, and no standards committee, hopping from one car to another will be extremely annoying.

Interfaces need to have strong couplings between action and zero overloading. Two finger ubiquitously means "scroll now" on trackpad. But even on an iphone, multitouch is seldom used for this reason. A trackpad has no images to display, so it is forced to overload gestures with multitouch. Phone don't have this limitation, and thus, intelligently avoid the use of multitouch.

As another anecdote, mobile games that rely on multitouch tend to not do so well.

[yalldraw]

Can you link me to the research you're drawing from?

[banachtarski]

I know this secondhand and first hand from the companies mentioned (and another I won't mention) but the actual studies are "corporate" IP unfortunately. You are encouraged to try different schemes yourself if you have a phone or tablet dev kit though.