People also tend to make in-groups and out-groups, but I wouldn’t recommend that modern societies designate an out-group to channel their hatered towards.
Sanctity and purity in and of themselves are nonsense concepts. They should be discarded, along with superstition and tribalism, on the ash-heap of history.
Like I said, I agee with Haidt’s description of how people work. I just think the conclusion shouldn’t be “therefore we need to accept that people are hardwired to be concerned with purity”. We need to understand that these are arbitrary concepts that perhaps had purpose in a pre-rational society (in the sense that many harmful things are also taboo; but many other things are taboo because they harm not people but the social structure that placed certain elites on top) but are now obsolete.