Agree - it's a common misconception. There's power in primary sizing & length & collector length tuning because it affects cylinder scavenging & filling, but it's hard for the average guy to do, so we use whatever's commercially available with the limitations and advantages that come with it, and all the while, trying to keep the vehicle street legal (or not). If you take a near stock car with all matched components and suddenly dump the exhaust, it might affect torque and driveability in the same way as when the guys in highschool would put a dual-quad tunnel ram on their 289 mustang, then expect it to be able to cruise at the drive-thru and use it for work 5 times a week. The exhaust should be tuned and matched to the cam & heads as part of the total system and set up for how the car is going to be used like the rest of the parts. The rules change some when you only want to go WOT, but backpressure in exhaust piping, itself, isn't a desirable trait of any exhaust system - it just causes heat buildup and pumping losses.

One reason an all out forced induction race car (ie: funny car or rail) needs pipes at all is to get the exhaust away from the car and keep the exhaust valves from being exposed to cold air. They also have so much power coming out of them that they affect steering & traction, so the direction they got them pointing is important.