Iron sights are enough at 300yds ON A MAN SIZE TARGET where you aim at centre mass
The whole point of the argument over sights/scope mag is down to the required degree of accuracy for the target size,
so the OP question "are we being sold a kipper ?" is down to what an individual shooter requires, for the target & range they're shooting at
PS, I never said I shoot rabbits at 200yds, although some people do, I was simply pointing out the previous highlighted statement was not true for that size of target.