[Troika]

I remember Higby talking about VOIP in an interview and mentioning that local channel is a possibility.
Since local channel is about 10-20 meters in radius around a player even in large battles you only chat with few people at any given time.
Local channel is good for shouting warnings at people who are not in your squad, and at least in Arma it works really well.

If someone is blasting music over local channel, you can always walk few meters away from him and problem is solved or put couple rounds in his head to shut him up. I have never had problems with griefing in local channel, in global and squad channel yes, but not in local.