I've seen on aibu people getting really quite nasty comments aimed at them (unfortunately it's just the nature of aibu) however if the OP decides to retaliate ... cue a whole load of comments like, why are you so angry OP?? You are really aggressive - glad you're not my friend.
I see aibu as a way to release stress of a certain situation, which the OP may already be worked up about anyway so they might appear angry - that doesn't make them an angry person.
And why should you just sit there silently having a load of abuse thrown at you and not retaliate without being called aggressive?