It doesn’t. In fact, it does the opposite. The reason they like to use it is because the discussions where it comes in are “soft”. In those discussions, there is not a simple fact that anyone’s viewpoint is dependent upon, so nothing can be “proven” one way or the other. But for some, the mere existence that someone would even want to have a discussion about something one finds so offensive is simply intolerable. So what do they do? When they can’t convince the person with this offensive view to change, they simply can’t let it stand. If they do, it’s as if the target of their dismay and dislike might have an actual legitimate point of view. That can’t stand. Remember it’s something the BCP or others have deemed offensive. So, they must now try to disparage the deliverer of the offensive message to strip it of any credibility. It’s a sign of weakness.
It’s akin to the need some feel to rally a crowd around them for support. It moves from, “Sorry, you’re not convincing me” to “Sorry, you’re not convincing any of us”. It’s a different tactic, but the motivation is the same, to destroy and ostracize the deliver of the offensive message. What cracks me up about both tactics is that the people who employ them really don’t be able to see that it’s a sign of weakness in one’s argument or debate skills. Usually both.