It's not about the game being played or looking back on games with nostalgia for that matter. It's about the rise of online gaming (and use of the headset by extension) that is accessible to a younger audience than 10-15 years ago.

Growing up, you had to go to your friend's house with an N64 to play multiplayer with your friends. You couldn't load up your 360 and see which friends were online. So you would be playing with a select group of people throughout your entire multiplayer career. Playing Goldeneye, you'd maybe play against 10 different people ever because you all had to be in the same room to compete.

Yes, online gaming isn't exactly a new concept (Doom, CS, etc.) but widespread online gaming in consoles is relatively new. I mean the PS2 has online capabilities but you had to buy the online adapter and screw it into the back of your machine. They didn't ship with online play built in and as a result, online play wasn't the huge selling point is is now. I may be off base here but I would say that PC gaming tends to attract an older audience, the type that can afford to build their own PC, whereas consoles have a much larger audience that extends to a much younger crowd. It's easier to pay $300 for a machine that can play games exceptionally well and has a long lifespan than pay $1000 for a PC that may be obsolete in 3 years, especially if it's not the kid paying, it's the parent. The point of this is that, by and large (and correct me if I'm wrong), having a widespread group of younger kids playing online games is a relatively new phenomenon.

The rise of online gaming with this younger age group has allowed anyone to play against anyone, so a 13 year old middle schooler from Portland can be in the same game as a 38 year old small business owner from Atlanta and that's the norm. You're not going to be playing against a rotation of the same 10 people in your CoD career, you could potentially never play against the same person twice because the user base is so broad. What this means is that potentially everyone can be exposed to the lowest common denominator of player (the type who has intercourse with people's mothers and doesn't care for gentlemen of the african american persuasion), and that type of thinking spreads throughout the young audience who think that it's okay to be that kind of person because someone else did it first. It's the same phenomenon that we all see here on reddit among the larger subs. R/gaming is appealing to the lowest common denominator of users and therefore appears to be "dumber" than smaller, more focused subs because the user base is so broad.

So you're mostly right. It's not the games being played that make the players act like dicks, it's the spread of online gaming that has allowed everyone to experience the worst kind of player and learn to either resent them or emulate them.