My Asus 1015PEM netbook from 6 years ago has a physical screen that slides over the camera; sliding the screen also turns on the camera. Why don't more laptops

My Asus 1015PEM netbook from 6 years ago has a physical screen that slides over the camera; sliding the screen also turns on the camera. Why don't more laptops have this feature if this is such a 'big deal'?