Do you talk with your hands? You probably do (most of us gesture when we speak) but you don’t really notice it while doing it. Only when asked about it or when it is pointed out in process do we generally notice. My bet is that these gestures are very consistent. That you make specific gestures when saying certain things or making particular points.
The thing about gestures is that they are deeply ingrained. They are as much a part of who we are and how we communicate as the words we say. Perhaps, even more so. When we lie, for instance, a trained eye can spot that fact in our body language. In this way, our gestures correspond to particular words, phrases, and intentions. Our gestures have specific meanings and expectations.
So, what does this have to do with the Mac and iOS?
As it stands right now, third-party developers have virtually created a wild west of gestures amongst and throughout various applications. A two finger swipe to the right in one app could do something completely different in another. In one app, it might switch the interface from dark to light. In another it may send you to a completely different screen. This creates confusion even with experienced users as we humans are especially prone to habit when it comes to gestures and touch. To us, gestures are linked to specific meanings and expectations. When such meanings change or expectations are challenged on a per app basis, it tends to betray and confuse our intentions at a very human level.
Which is why I think, especially with the advent of iOS 7, that Apple should help to define and guide the use of gestures in 3rd party apps with an official addition outlining their use to the Human Interface Guidelines. I believe Apple should set a standard for what specific gestures should do and what results a customer can expect from them. While I don’t think these should be enforced through the approval process, I do think it should provide developers with a baseline as to what users should expect a gesture to do and that not doing so means you will be working against said expectations and intentions.
I want to state that my expertise in this area is that of a user’s and not a developer. For all I know, such guidelines may exist (though I looked and could not find them). What I do know is that for now, I have to remember and learn dozens of gestures that are specific to each app and find it crazy making at times. It would be nice if there was some consistency.