Hm, odd question. I have thick skin. It's impersonal to me and nothing said would be bothersome if someone did it in reverse. It helps weed out those with weak resolve.

I'm naturally a rhetorical showman & enjoy flair; provocateur, partially because for me debates a blood-sport. Also, when you're arguing against many who disagree unconstructively to defend your views especially when no-one shares them you must be adamant.

Lastly, it's partially social engineering. Prodding(pushing their buttons) people has tendencies to cause the volcano to erupt. Manipulation it's an important part of persuasion and utilizing different tools at different times can turn the argument in your favor(studied with public relations/lawyers/politics majors) Encouraging your opponent/adversary to make gaffes & faux pas can strengthen the reception of your arguments; while at the same time: this is my favourite one.

When people are upset the emote painfully. Their views become transparent which makes it easier the pin them down and drive then into a corner. Debate goes faster, more efficient way of maneuvering yourself.