It's easy to understand the point that window management in Android is complex and this complexity hampers graphics performance. On iOS, one process has the entire screen at a time. There are no widgets, no plugin viewports, no 3rd-party UI - but all this stuff is happening on Android. The question becomes whether this is actually a good paradigm to have for a mobile platform and whether this compartmentalization mechanism is really needed.

For example, take this statement: "This [window management technique] is also why Android can safely support third party input methods." Clearly, the perception at Google is that this model makes Android safe, and in a way that's understandable because the platform is way more open than iOS and thus needs more inherent resistance. But look at the concept of "safe support" for third party input methods. But does compartmentalization of UI operations in this case actually make, say, 3rd-party keyboards safe to use?