queue the tumblrina's with "just because it's on the internet doesn't mean it's not real"
Which is false, that's exactly what it means. A random internet meanie saying something that bothers you is kind of like letting a barking dog hurt your feelings. =/
A barking dog might not hurt anyone's feelings, but one that's growling and running at you is a legitimate cause to assume you are in danger and react accordingly. Lots of trolls aren't saying "your mom's fat", they're saying "I'm coming to kill you in your home at Hummingbird Line 1".
Another problem with your analogy is that a dog barking at you doesn't affect how any dogs you might meet in the future interact with you. On the other hand, humans take their cues about how to behave and even how to think from their environment. A random internet meanie saying something that bothers me makes the ideas they expressed seem more acceptable to anyone who hears him, thus shifting the culture into a direction I don't like. That's how propaganda (and brainwashing) works: if people hear something repeated often enough, they start accepting it as truth, or at the very least accept it as something the group believes and thus they must at least pretend to least they get excluded, no matter how absurd it might be.
So, whether the Internet is a magical wonderland outside of reality or not, and whether people using it have or should have the emotional sensitivity of rocks and the willingness to be virtual punching bags, it doesn't matter, since the crap you take on others there will stink up reality too. And that means its going to stop, the only question being whether it stops because people stop acting like crazy assholes, or because all the crazy assholes are busy making Bubba the Prison Rapist an insanely happy man.