Guess what rookie, it doesn't sit because we're bad timers, it sits because we understand physics.
When you take that shit off the grill, it's not done cooking. The juices inside the steak are still very hot and will continue to cook the tender inside of the meat while the tough, grilled outside doesn't overcook. Ask any chef who knows what they're doing (you know, professionally trained, makes their living off the quality of their cooking), all of them will tell you to rest a high quality steak.