Comment by iggldiggl

> The main benefits is that Google is able to optimize downloads for individual devices.

I don't think Google does the more invasive bit of stripping out non-applicable code protected by API level checks (Build.VERSION.SDK_INT), and otherwise, the simple splitting up of native libraries by ABI, graphics resources by display density and string resources by language (plus any additionally defined code modules for on-demand download of optional features) could have been done wholly locally, too, including signing.