The end is you getting out of a conversation that annoys you with total disregard for the other person's feelings? Because the way shokwave phrased it is really incredibly blunt.

There are plenty of unproductive discussions in rational circles where you can reasonably assume that the other person is arguing to win a debate and not because he finds a discussion interesting.

I think those discussion are situation where shokwave might say those words. In those cases they are spoken with the interest of the other person in mind.

Of course you can be wrong about that in your reading of the situation. If you pay attention to the other person you should notice when they have a meaningful emotional reactions to the words that you are saying.

In those cases you can readjust the emotional impact by telling them something nice about them and starting a new thread of discussion in the process.

While I personally wouldn't be as blunt I have meet plenty of people who have no problem being that blunt while also doing enough to signal that they like the person they are interacting with to avoid harming them strongly.

Additionally I would personally prefer that if I'm walking around with body odor that someone would tell me, even if he would tell me in a way that produces a bit of temporary emotionally displeasure. I would predict that a significant amount of people who are part of the rationalist community share that preference.

I like getting honest feedback from other people. If someone puts me in a state of deep emotional turmoil I think they are responsible to stay there and do what they can to fix it if they aren't requested to leave. But to the extend that I do have control over myself I won't look down on them for providing honest feedback.

really incredibly blunt

It's possible that it is too blunt. My instinct (calibrated on around half a hundred nights of conversation with Australian LessWrongers in person) says that it's not, though.