Should I ground the metal box of NEMA 14-50?

Weekend keyboard electrician here, I am putting together a NEMA 14-50 for my EV charger. I used four 6 gauge THHN wires (green black white red) through a 3/4" PVC conduit to a metal box with a metal faceplate, by the way it is a hell pulling four 6 gauge wires through a 3/4" PVC.

My question for the real electrician here, most YT vids I watched just directly wire these four wires to the receptacle (2 hot, 1 neutral, 1 ground), but I recall the ground wire should wire to the metal box, and then using a clip to connect to the receptacle ground? What is the consequence if the metal box is not ground in this scenario?