Over the last 24 hours, Google has been sending notices to developers worldwide stating its intention to “limit visibility” or remove apps from the Play Store that violate the company’s User Data policy.
The truth is, once you download an app, the app owner and ALL of the other apps on your device, know. Your device becomes a cesspool with each app sharing info.
And it isn't just privacy, it's permissions too. Some apps not only have access to the info on your device BUT can also control the hardware (camera).
Keeping applications in the cloud, and not on your device, would go a long way of helping with privacy and permission issues.