Dude, it's the internet. If you don't want to get trolled or messed with on the internet, then duh, don't use the internet. And as Bottiger pointed out, most players are still in high school. Some, junior high. Every TF2 group is going to have people who are hostile to each other. It's called life. Just because there's a certain amount of people who are dicks in a group doesn't mean all of them are.
And just pointing this out but if you're complaining about people being hostile on the internet, doesn't that make you a bitchy high school kid? I'm not in high school anymore so I wouldn't know but just saying.