One cannot engage in the politics of personal destruction if he does not know the in real life identity of his target.
Anonymity keeps the discussion about the topic and the merits, and makes it more difficult to lob personal insults. As long as the anonymous poster's statements are consistent and truthful, then the attacker is left with debating only the merits. That's rather difficult when the facts cut against the attacker.
Case in point. I have revealed that I am a in real life lawyer, so Mr. Bot takes pot shots at that fact, protesting thusly about my question about how JSJr kept his 7/27/1842 wedding vows to Sarah Ann Whitney to 'preserve' himself for her "and from all others", labeling it sarcastically as a 'courageous anonymous rant':
Mr. Bot this morning wrote:I wish there more non-anonymous believers willing to come in and respond to your courageous anonymous rants (so unheard of, really, for a member of the Bar to stoop so low), but you have me once in a while.
If the discussion is to stay on substantive topic, then anonymity is a tool to further this purpose in that it deprives the Derailers of their own tool to try and make the thread turn into personal insults that go with one's in real life background. It has to be frustrating when there is not more in real life information about a poster that a Derailer can use to throw a thread off course.