The moving part has nothing to do with hitting a target at 300 yards. 300 yards isn't an impossible shot to make. In fact, I would say that any rifleman that is considered competent would be able to hit such a mark a high percentage of his shots.
Hitting a moving target however is in fact nearly impossible, but not because 300 yards is an abnormal distance. 300 yards increases bullet flight time, allows wind, humidity, temperature, gravity and etc to have a huge effect on a bullet's trajectory. Couple that with the fact that a human running perpendicular to the shooter is fairly thin. You have to calculate the flight time (Very little, but remember, you only have a 6 foot tall, 1 foot wide target, so inches matter.) and then calculate where the runner will be in when you fire, and etc. It's mind boggling in it's increased difficulty.
More to the topic. The Zoom function is actually fairly realistic in my opinion. In fact, I'd almost go as far as saying it's almost not far enough. For example, go out to your local (American) football field and send a friend to the opposite goal-line. He's not very small I'd imagine. Hold out your thumb and compare his size to it, I'd guess he's 3x as large?
Well, if that's the case, around 300 yards he'd be the size of your thumb. In RO1 a head at 100 yards was smaller than your front iron sight, at 200+ yards the entire body became smaller than your sight. Since I'd assume your iron sight is smaller than your thumb, you can judge the accuracy of RO1's views at distance.
In RO2 this is much better, I can accurately see a head at around 200 yards in good light, and can easily shoot with competency at 300 yards, which is a good distance. So, while I think perhaps it could be justified to zoom further, it DOES mirror reality.
Just my thoughts, feel free to disagree with my ranges and etc.
