Aaaaand... BINGO! I think I counted all of the current Buzzwords in that one.
Of course people are self-righteous on the internet. They can say what they want in a 'fire-and'forget' mode, with no repercussion. They can type in constant extremes, thinking about what they say and how they say it without the pressures of having to think on the spot and say what they really feel like in actual conversation. They don't have to deal with the fallout of insulting someone face to face, and don't even have to see the response from their probable misguided opinion. They get to make their point and juctice is served.
You then take the demographics of this site into consideration. We like games. We like geeky shit. We were probably (as a collective) in the upper third of our school academically but the bottom third socially, and we didn't care. We concocted opinions and morals silently without sharing them... and then... BOOM. a medium came where we could express ourselves without the awkwardness that came when we tried in real life. We were not conditioned to this type of discussionary interaction, and we are probably doing it wrong. Then again, we have been for years, and it is now the norm.
It is probably safe to say that a majority of people here are those who shy away from conversations such as the ones here in real life. I know I do. I am one to avoid conflict in my life, but on occasion can be drawn into arguments online where I will say things in ways I would never dare if sitting in an actual group.
An example I have from this site that backs this is in the user groups. I was a member of some of the bigger active groups like the Brovengers and the Injustice League and the discussion in those, whilst usually civil, could get heated, partucularily when discussing something with opinionated. On the other side I attend the UK Escapism meets (when work allows me) and am a memeber of that group. Nearly everyone in there has met others in real life, or will at some point and that is why they joined the group. The way people talk and act there is very different and is always civil. Then in real life, at those meets, there are never actual heated opinionated discussions that aren't quicky reduced do to the effect real life and tact has on the situation.
So, all in all, hiding behind a screen pouring your inner thoughts and feelings that have been brewing over time definitely changes the way you act around others, and the way you would usually tackle a subject.