I don't really agree with that theory.
You might be forced to make a head shot, a hostage rescue shot, a long range shot, who knows. You could see a guy across a 6 lane highway beating up a cop, take his gun, and put it to the cops head to execute him.
It would suck to not be able to intervene because you have an inaccurate point defense gun.
Also, i find that the smaller a group you can shoot when calm, the smaller the group you'll also shoot while you're all juiced up with adrenaline. I have this view because of my experiences hunting live game.
I can do this with my LCP at 25 feet (I jerked the trigger on the last shot and yanked the bullet low into the 9 ring- user error), should i take it back and get a gun that's less accurate?
Should i not believe that it is a net benefit that my P7 can do this at 10yds with full power 9mm+P JHP ammunition? Something very few service grade pistols can do.
I believe in accurately placed shots. I think they trump caliber, and i think they trump bullet type. All other things being close to equal, i will choose the more accurate pistol, rifle or shotgun every single time.