One can Open the proper way, as you have been doing - the crack may have occurred during the Closing process. A Pen, wire from charger basically anything that come between the Display and keyboard can cause the crack.
Hope one uses the exact same method of closing the lid as used for opening. Have seen many people claim cracks happen when adjust the screen angle with one hand BUT grasping the screen bezel for a corner. All the Physical Energy transferred from Hand to Bezel on one corner caused torque Energy to warp the screen and Cracks in Display occur. The Two hinges require equal press to function as Designed.