If you want an explanation: that kind of name-calling is an attempt to use your authority to diminish someone else's standing. It has up to two effects: it either diminishes that someone's standing, it diminishes yours, or both. I think the effect is decided mostly by how much authority you as writer have in the opinion of the audience.
If you don't have much, you risk a reaction such as "oh, that writer is just another name caller in the peanut gallery".