One of the most horrific wreaks I have personally seen was a low 12 second S-10 that blew mid track and knocked out the right slick. By the time it was over the truck was on the guard rail with the cab, pivoting at the front bumper, upside down in front of the chassis, driver hanging upside down as well. Engine containment might have prevented this.

One car, blowing an engine with a containment device, might be the difference between finishing a race and not. And when you drive 600 miles to get there.....