Both of these are game developers. So I think that at the moment the type of app you are developing may effect how easily it is to get good compatibility. Also the type of markets you want to tap may matter.
Yep - the more specialized and low-level it gets, the more stuff will break on devices you have not tested - that's what I mean.
UPDATE:
Perhaps I should tell about my background here: I have been developing Android apps since 1,5 years now, among them an app for my master thesis which makes heavy use of OpenGL. One xample of what can break: If you load OpenGL textures, you should choose a texture size of 2^n pixels - or at least I found out when they did not show up in some of my test devices. Some newer devices showed the non-2^n-px texture (500x500) without problems, but older did not display anything. Now imagine you code a game or interactive info display - is that the kind of issue you want to have? You won't run into this issue on iOS, because there are only so many OpenGL drivers.
Apps like Pocket do not touch these issues, they don't do "hard" things.
Perhaps they are bad developers.
The guys with the 4000 Android devices explain what they are trying to do here: http://www.animoca.com/en/2012/05/the-varieties-of-android-e...
Both of these are game developers. So I think that at the moment the type of app you are developing may effect how easily it is to get good compatibility. Also the type of markets you want to tap may matter.