Well, you name quite the case, but besides that. I think the fact that anonymous discussions derail easier and don't exactly get the best out of people, isn't relevant at all. I would even say, it is a price, we should be willing to pay.

First of all being anonymous is important if you want to call out far more powerful entities than you, which can lash out to you. Second I think it is important to see, what the darker side of society thinks. Even if you remove them from the normal internet, they will still find a way to communicate, but now it is no longer out in the open. It is better to know then to not know.