Hardcore does seem to be the place for people who can't compete on the proper game .
I can't agree with your sweeping generalisation of players I'm afraid. Whenever I'm in a game there are a lot of snipers and AR users and if everyone is constantly sprinting that would mean they would be easy targets as they couldn't shoot quick enough.
Very big of you to admit that you can't compete but the rest of your post sounds like you haven't been able to transition your play style and you are looking to name call others who are successful in an attempt to deflect some of your failiure away from yourself.
Ah well... don't let the door hit ya and all that.
Yes, that is the whole point in the post, telling people why I suck lately. But, I'm not name-calling others. I am almost constantly outplayed by a team of SMG sprinters when playing solo. It's a very powerful and fast paced style of play, something I'm not used to both using and attacking.
Put me in a game of mainly AR users and snipers and I'll dominate, but these games are few and far between.
And what's the "proper game"? I'm guessing a lot of Hardcore only players here would tell you they're playing the proper game. I on the other hand take the whole of the game as proper.
BTW, not once did I say "I'm done with this game" or "I've had enough, I quit" so I won't be opening any door to be careful not to let it hit me on the way out 
Mind sharing what it is that you've been doing since MW? Explain with detail your gamestyle.
Holding down an area, making sure the enemy could NEVER kill us from behind. Advance slowly and tactfully. Knowing that holding two flags in Domo is all you need. Knowing that rushing the enemy spawn is a tactic for noobs and idiots and causes more problems than benefits.
If you have a team that know how to control spawns, you can destroy the run n gun players. The problem I encounter with holding down an area, is a guy end up spawning with a clear shot on me. If your team isn't all trying to rush to the other teams graveyard, they'll keep spawning in the same spot, making thier pathing more predictable.
Yeah, I agree with this. My problems are only ever when playing solo.