Third-Party Dynamic Wallpapers on iOS

Why aren't dynamic wallpapers from third-party sources available on iOS? This feature (termed "live wallpapers") was implemented on Android over a decade ago. I can't imagine a reason for not adding something similar to iOS (the stock dynamic wallpapers get old pretty quickly). Of course, excessive battery drain would be a concern but a simple disclaimer when the user is setting a dynamic wallpaper should be enough to make it clear that the problem is not with the OS, thus pre-empting any battery drain-related backlash Apple would receive from adding this feature. If there is concern over the app running in the background, couldn't some special rules be made just for live wallpaper apps? It just seems like something that should have been added a long time ago. This is the biggest thing I would like to see in a future iOS release.