I made the mistake of just blowing this off, but I just read a Physics teacher make the same claim on another web site. Bullets are spin stabilized unlike arrows that are fin stabilized. So back to not arrow making 101 but to "Arrows for Dummies" as in the books. Amazing the BS spread among the general population. I read that rifling was conceptualized because they knew that putting a spin on arrows made them more accurate. Easy for me to believe. When I first started making arrows I had fine luck with field points and straighter fletching than pictured but when I went to the broadheads as pictured they did not shoot. I found, like an individual that is very disappointed with a custom Minnie mold for his 40 that he paid dearly for, that they needed more stabilization or spin. When I went to a pro shop to buy feathers, I wanted left wing and he only had right wing. Why? Because right wing was popular and did not loosen the screw in inserts on the aluminum arrows his customers shot due to its spin. You see straight fletching on school arrows and cheap training arrows but they are BB gun ammo. Conversely, when I shot 3D last, the unlimited class were using carbon arrows with about 2 inch straight fletching. It required very sophisticated arrow rests, and a trigger release. An arrow that does not spin with that small of diameter maintains its 300 fps velocity longer and shoots flatter. Far less drag than the turbulence created by a spinning arrow. Something 3D shooters value. Arrows were checked for straightness on a dial indicator, with very small diameter arrows and bullet tips. These are the smoothbores of the archery world. This example is what leads me to believe that a smoothbore requires extra care in loading for accuracy. Forget the dimples and look at technique and quality of your components.
The reason we use rifling or spin stabilization is that it compensates for imperfections. Those arrows I mentioned were the "perfect" arrows. The bows are tuned by shooting through paper to see if there are any oblong holes. A few of those same people that used them, switched to spin stabilized heavier arrows for hunting as they will not stabilize broadheads. If you make wooden arrows you will get more arrows that shoot if you spin them. That had to be important in the early days. As to subsonic issues. The application of these principles hold for arrows, pistols which are subsonic and extra fast rifles. Last I am going to say on this issue as we are really wandering. You can argue these points but aerodynamic specialists writing in archery publications will support me. Its as basic as it gets.
DP
