Abrasive people are people who really don't care about hurting other's feeling, because they think thruth is of the utmost importance; so, the tend to speak the blunt truth even when it isn't advisable to.
The point of this is: why don't 2 abrasive people have a positive reaction towards each other? It's so hard to find people who like to always hear the unmitigated truth (speaking from experience here).
Just my 2 cents. :)
My interpretation of abrasive was that it was intended to represent someone who is a lifelong bully. They continually insult and demean those around them out of a combination of habit and some internal need to feel like their better than someone else.
You put two of those in a room and they'll just duel it out with insults until someone gets a punch to the face, which is essentially how it already works in Rimworld.
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Someone who is just perpetually blunt and truthful in their interactions is probably best represented by some who has very low social skill and passion (or who has it disabled entirely). They can still have positive interactions with others, especially those they have a lot in common with, but on the whole, many people end up feeling like they've been more slighted by them than anything else.
That's my interpretation at least. Rimworld interactions aren't really the most nuanced to begin with.