Yeah, it drives me crazy... I had a brisket last weekend that was like chewing leather because they sliced it right off the smoker. All those hours of cook time just wasted. Even my cheap ribs at home get a solid hour wrapped in a cooler, and they turn out way better. That rest lets all the juices settle back in, it's not even a secret.
Used to skip resting myself until I ruined a pork shoulder by cutting in early. Saw all the juice just run out on the board. Now I won't touch anything without at least an hour in the cooler.