and quickscoping gets rid of the balance that snipers are supposed to have, their big weakness is supposed to be that they aren't effective at long range, quickscoping gets rid of that weakness and makes the guns unbalanced
I've really never saw a game which balenced the sniper rifle since they usually make other bullets from guns really weak since you can spray and snipers one hit kills since limited ammo and long reloads so if there is a limited amount of people you could just run around and one hit kill everyone while the machine gun requires a longer time to kill and have alot of accurate placements of the bullets while the sniper only needs one accurate placement.
Actually one game I played balenced the sniper rifle well(actually in the game it was your hand) by having it where if you didn't scope in it would barely do damadge and you needed to "charge" the shot by scoping in for about 5 seconds to get it to max power.