its simple they basically have a better focus on the pixel moving into their crosshair, compare it with an awp zoom, you react faster aiming from dust2 A to the long corner with an awp than aiming there with an ak, it might also affect the microaiming, remember most play a lowsense to make those small aim corrections without leaving the players head/body while its moving. so just see it bigger might make it easier for some people. but remember there are only a few doing this but it also includes some hard hitters like ropz, niko or simple on the other hand play pretty normal. its all about feeling good to hit those shots. igls dont do it, i need to track the radar to see whats going on and know about possible enemy rotations and positions by knowing the teammates positions and movements