I've gotten dozens of kills in built up urban areas during games using just my rifle. Have also gotten only a kill or two when playing outdoors in the woods, sometimes an easy dozen. Really all just depends on the way you use the system, the system being you, your decisions and your rifle. I've noticed the way I play the airsoft sniper role is very much the same as I do when playing video games, so I can pretty much prove that the two can be similar. Still, both have their places within each other, you can learn and improve from doing both.
Here's a pic of me rocking an urban type environment with my M24. My MP5 is up against the van, but for this day, I never even used it. Check out the fact my placement gives me a line of fire UNDER the van, worked great!