I remember reading the idea expressed in this quote in an old LW post, older than Haidt's book which was published in 2012, and it is probably older than that.

In any case, I think that this is a very good quote, because it highlights a bias that seems to be more prevalent than perhaps any other cognitive bias discussed here and motivates attempts to find better ways to reason and argue. If LessWrong had an introduction whose intention was to motivate why we need better thinking tools, this idea could be presented very early, maybe even in a second or third paragraph.