Why does nobody ever speaks in this game?

I've had Space Marine 2 for a week or so and I've been playing a lot the past few days. I play with my mic online and I'm very friendly with everyone, always taking to them as they respond in take with emotes or other things. I've noticed, besides for one game, no one ever speaks. Sometimes one of my teammates will turn their mic on for a moment to say something, but they will turn it back off and keep it off. I can't name more than 3 people, our of the dozens I've played with, that have actually had open mic, even then, I had to leave through the middle of a mission with 2 guys who spoke. So, I'm wondering, why the hell does no one say I God damn word in this game?