I also put the unused and seldom used Apple apps into a folder. One issue with that method is that some of those apps might be able to phone home, so to speak. So I make sure to turn off cellular data for them. They might still be using WiFi though. Not sure about that. Another issue is notifications. I also turn off notifications for all of them.

The problem is that they are likely still able to phone home and retrieve, and thus store, data. So they are leaving a data footprint on the phone. The fact that they still can run in the background means they have a power footprint too. So they do impact battery life to some degree. I'm not sure if deleting them actually addresses these issues are simply hides their app icons.