Quick scoping by no means ruined the game. I think you may be getting trickshotters and quick scopers mixed up. Quick scoping takes accuracy and you have to play smart. You have to control your engagements, because you will get beat if you turn a corner right into a guy using a shotgun, or someone head glitching with a Type 95. But yeah, trick shotters can get annoying when they're going for suicide shots and make you loose the game.

Lots of "experts" on how the game works and should be played this morning...

I also find quickscoping with the sniper rifle to be extremely annoying, but I'm not really affected by it since I am usually sniping. Which means I am hidden, undetected, and out-of-sight. I am almost always in prone, always have a trophy system up, and a claymore nearby, and I will stare down those crosshairs for as long as I have to. And that's just how I play; don't like it, then quit. But I do disagree that it doesn't take skill. While luck is a factor when it comes to quickscoping, it does take some trial and error and practice to actually get it right. I have been playing MW3 almost religiously since it was released, and I JUST recently got the hang of being able to walk and shoot (meaning able to look down the sight and shoot, while standing and walking/running) with the MSR at the same time (and I'm glad I did, because my KD went up). But I will always be a hardscoper, because that's what you're supposed to do with a sniper rifle. Not to mention that I get many kills with this method. So I'm not going to try quickscoping any time soon, since I know for a fact that a majority of them die more times than they kill.