On consoles they have aim assist to help players aim. It's not like autoaiming/aimbot, but rather when a player is within your crosshairs the game will "tug" the crosshairs along with the players movement.

Quickscoping is where people will run around with a sniping rifle and quickly press to scope-in then fire off before, or immediately after it is scoped in without actually looking/aiming. Because of the aim assist, while they are scoping in it still tries to keep their crosshair on the target, it makes it pretty easy to not worry about aiming and just scope-in/shoot--as long as they start with the crosshair remotely on the target. They can do this from most ranges(because sniper rifles aim assist works at a pretty far range since they are supposedly for long-distance combat. This means snipers can cover any range safely, long distance, medium, even close, because of their 1hk potential.

In my opinion it is an abuse of the mechanics and imbalances the sniper "class." It's not like noscoping(which is exactly what it sounds like) because that's purely a luck thing.

I don't know why they don't do an inverse-damage drop off where bullets do minimal damage to start and gain strength the further they get.