I don't understand either. It's not like they don't also control the code that perform the signature verification. I don't really know how app submitting/build

I don't understand either. It's not like they don't also control the code that perform the signature verification. I don't really know how app submitting/building/signing works on android, but I'd say the main issue it could add would be that the application can be tempered with between the moment it's built until the moment it's signed by Google.