I don’t believe the OP was asking if people are doing things or if there are useful applications, but rather if there are useful applications that can only be done, or done better, in crypto.
Oh, thanks for the context! I never owned a Windows phone, I just played with ones other people had, same for Android. And from a total beginner perspective, Windows phone seemed a lot easier and more intuitive, but I can believe that with more use its annoyances would become more clear.
That's interesting about Microsoft really trying for mobile. My recollection is that they didn't put much effort into it, but clearly I was just unaware of it. Which is, perhaps, a sign? For all its investment, perhaps it didn't have the right marketing, as I was never aware of Microsoft's efforts for Windows Phone the same way that I am for Android and iPhone.
It was pretty good. Seemed better than Android at the time. I'm not sure why Microsoft didn't put as much oomph into it as they did for, say, the Xbox, but if they had it might be a major player now.