If more people took the concept of don't be a dick just because you're safe behind the keyboard, I don't think we'd be where we are now.
I should have used a less violent example. We are social animals, breaking social rules leads to consequences(often implied and often trivial).
Abusing people in real life breaks social rules, which means that you feel bad. (in most situations, bullying is a notable exception, but again that's based on consequences, the abused party continues because they fear the consequences of not conforming. )
In the online world, you don't see the results, there is no person getting upset, there is no relationship, there are no friends that see you be a dick and shun you. its just text, its easy to "other"
Which was the entire gist of the OP, no? Perhaps I misread / misunderstood.