> In Windows Phone it is also possible to sideload.
Good to know. I was under impression (since WP7 was a current OS, I admit) that you have to upload to MS/have it signed/download.
> Still, nothing would prevent such stores to offer a server compiler service.
Nothing prevents that technically. However, it would mean a tighter coupling between platform owner and majority store owner, Google probably wants to avoid that. It could destroy the open-source nature of Android, since for now the Play Store is layered above open-source platform; this compiler would not fit there, it would have to go below, into the layer that is currently open source.
In Windows Phone it is also possible to sideload.
> Or you can develop your own app totally offline.
You can compile .NET to native code via release builds, before deploying it to the Windows Phone.
It is only when you upload the appx to the store that MSIL is still used.
But I agree that with Windows Phone and now with iOS going bitcode as well, there isn't the issue of third party stores.
Still, nothing would prevent such stores to offer a server compiler service.