I think it's indeed more convenient to talk about things without revealing your age, gender, appearance etc. But in general right people is the key to establishing a productive discussion, no matter whether it happens on the internet or irl. It depends on the person, its mood and ability to pay attention only to arguments, to tolerate other people's opinions or even criticism, ability not to bring it down to a personal level.
As for me, unfortunately I'm not one of those reasonable people. So if we hold opposite visions, I can't stop myself from looking at you as though you are inferior to me and you have to be punished for having a wrong judgement. Especially if I know you. I even cut off all contacts with my friends because there were differences of view on different (often silly) topics and I couldn't put up with that.