"When was it that gaming became synonymous with dude-bro culture?"
It's not. That's a rather silly oversimplification, to be honest. Gaming has simply expanded to include a ton of different demographics. I don't see how it's synonymous with any one subculture at all. Ask an average non-gamer and they'll probably still answer that games are for kids, or nerds, or perhaps for everyone.
As for when the "dude-bro" crowd came in, it's really just that kids grew up and joined different social groups, which is natural. A friend of mine that I used to always play Nobunga's Ambition with on the NES ended up getting hooked on Medal of Honor and SOCOM. He was crazy over them, had the headset and everything. His path in gaming just ended up being different than mine. I'm certainly not going to condemn him for that.
The sports franchises were huge about bringing in non-gamers, as well. At the video store where I worked, we'd get massive rushes of sports fans every year who rented pretty much nothing else except sports games and GTA.
People really need to get over this idea that they are somehow superior because they like a different genre of video-games, or that other people should be mocked if they play something mainstream. I know regular people who play nothing but CoD because their coworkers pulled them into it. Who cares? They're playing games and having fun. The "dude-bro" gamer is just a small, overly-vocal representation that's mostly limited to competitive multi-player games.
