A must have to give elements relative position to parent/siblings. With a relative layout you can play not only with X/Y but also you can play with width and height.
Example: place this button relative to this image at X = 50% of image width and Y = 70% of image height. Give the button 25% of image height.
Xamarin.Forms has this already and it is really useful. AbsoluteLayout is good but not enough. You can only position elements related to parent.
|Link to GitHub issue|