IMHO, most people who misbehave online are decent people that get carried away in the emotion of the moment. If the community calls them upon it and force them to own up they comments, they will probably appologize. This requires explict rules and bounderies, as well as the community being able to disengage the minute the infractor does not show any signs of remorse.
On the other hand most online misbehavior comes from a minority of repeat infractors. I am willing to believe that the majority of those are not checkbox assholes, but inmature individuals that do not know any better. However, I do not think trying to understand them and accomodate them do any good to either the community of the asshole-to-be. The best online communities I have been part of do have a sort of virtual sign at the entrance saying: "Your manners have to be this tall in for you to ride this game."
If you fail to meet the requirements, your posts are erased (or never put thru in the first place). In an ideal world, a moderator may contact you and invite you to express your point with a minimum of decency. If this cannot be achived by personal message, a broadcast announcing an otherwise worthwhile post have been deleted due to open disregard for civility rules can be an acceptable compromise.
Finally, there is such thing as a "checkbox asshole", and nothing you do will make them change, because they trive on negative emotions they trigger. You just dont feed the trolls, keep hellbanning them over and over, and hope they get tired and go trolling elsewhere.