Quick scoping does have a tactical position in mw2...at least for me. I often run intervention with any quick swap weapon so close range if I miss a qs I can still take the enemy down. But at mid range using a d-eagle or pistol is not nearly as easy as just quick scoping the opponent. But tbh there are alot of noob quick scopers around and unless your going to get good with it then there is no tactical position of qs'ing. But anyway if you can combine a mix of hardscoping, quickscoping and using secondary when you for example or jumping everywhere and obv can't hit a halfscope midair lol then you would have a pretty strong tactical advantage over your enemy.