Welcome to the forums, Sevren!
I can't comment on TF2, but for World of Warcraft (which I have played) there seems to have been a move in the last 4 or so years from the experience to taking it seriously and doing the best you can. But that's based on more people at higher levels (and low levels more often in the alts of high levles), and the need to be specialised and take it seriously in order to play the new instances and raids (e.g. especially killing bosses).
Bill Tiller talked about this in our interview with him... "I was playing it recently, and I grouped up with some other people and they said: "Oh my God! You’re level 42 and you don't know how to group! Such a noob!" I had to work out all the party etiquette. I said: "I'm sorry, I solo a lot, that's all.""