At what age group do you stop seeing teams/fans who cheer/chant/yell/make loud sounds, display obnoxious behaviors, etc.? I remember one team around the metro area back at the 11u age who did some of this. I don't recall seeing it at 12u. To my surprise, during a recent tournament at 13u there was a team who did all of that plus stomped on the metal stands throughout the game, hit cups on the stands for noise, and yelled comments to the opposing players. Even their players looked disturbed by it. Sure hope 13u is the end of this. I can't picture fans acting like this at high school games.
We have seen very little of this at 13u, but now and then we'll get a team that hasn't grown up yet. Your experience sounds a little extreme. Sounds like a rowdy group of football fans found their way to your baseball game.
The cheer/chant/yell/making loud sounds in concert should end at 12U; however there are coaches out there that encourage their players to act in this manner. The last time I saw this behavior was women softball players. I don’t like it. I told my boys to adapt to the Bobby Cox way of encouragement. “Let’s go kid”
You will be surprised how much still goes on in High School when it comes to rivals or important games. The rip rip rip louder. The chants of good eye, good eye, goooooood eeeeye after every ball. The bench yelling back after a pick off throw when the pitcher is delivering his next pitch. So don't think it is going away until the coaches make it go away.