It's the attitude BEHIND the words. Every match there is blaming going on, even when you're on the winning team. The words being said are pretty mild by internet standards ("omg you suck", etc) but the constant negative attitude just drags you down. It's so hard to stay positive and play well when every game you get blamed for something. Again, the words being said aren't really that offensive or "bad" but being faced with the constant negativity every single match wears you down emotionally until you start lashing out at anything even mildly negative.