I know how Lusche does it... at least in a tank.
He's got the optics down cold, and one of the few times I ventured into a tank he killed me from if I remember right between 4 and 5 KM out. It's been a while, but I think I it was on the 3rd shot - what I mostly remember was I hadn't even figured out what general direction whatever was shooting me was by the time I was dead.
Folks can argue that they are lame for doing so, but one thing I know for sure is that the guys who end up on the "front page" do so by do being far far better at most of the game - and perhaps everything in the game - than I'll probably ever be.
So... if that's their thing, so be it, more power to them. If it happens to 'em by accident, so be it, cudos. And if there are plenty of players better than one or some of them that don't, then... so be it.
<S>