Seriously, if you can aim straight while jumping. Why should it be disadvantaged? If anything it disadvantages the jumper, because their movements are more predictable, once in the air there isn't much change in direction. So if you guys have a problem with that, you mustn't be as good as you think.
And these people never siad they were good. They are environment asrtists, they didn't create the weapons system or any of that. They simply made the environment. So the only advantage they'd have to normal people (even not really) is knowing the map better.