Personal experience tends to back this up. I can't think of anybody in my immediate circle who actually paid for something in the last year on their iPad/iPhone.
Relying on anecdotal evidence is always tricky - nobody in my immediate circle ever paid for anything on their iPad/iPhone. But anecdotally, most iPhone devs I know consider discoverability to be a potentially platform-killing problem, and are finding that they can't make a living as indie devs because it's too hard to surface their app. Other platforms like the web don't have this problem, which might explain why webapps still get a lot of attention even though the iPhone userbase is now a much larger share of time spent online.
I literally do not trust buy-only apps anymore because of it. For example I wanted to log my gym progress in an app, and I had to go through at least 10 different apps before I finally found one that had the functionality I wanted (fitframe devs thank you!).