[bene_legionary]

Being anonymous is a big part of this. There is very little consequence of being controversial online if you're just another person posting (and not, say, a celebrity where your presence means something offline too). The most might be people noticing that one particular person is stirring up trouble (and block them). Offline conversation has the benefit of being in real time. The other person almost has a social obligation to listen and respond. In addition, you know it's a real person that you're talking to (although, with people spending more time online, their real-life etiquette has changed for the worse; people shout, berate and threaten others like there is no consequence). Online conversation is static; you can ignore it, and nobody will know. Anybody can read it at any time as if you were continously shouting it. Nobody is obligated to respond or pay attention. You have no idea if the person responding or commenting is real, or is just a bot, or is a troll trying to make you irrational and angry. It's terribly confusing.