In Kahga's defense... these people did literally come from hell. I dont give a shit what your story is, if you are from hell and at my doorstep asking for a place to stay.... I'm gonna tell ya to kick rocks too. You had to do something bad to get to hell in the first place.
That... isn't how it works in D&D. Their very existence is due to demons breeding with other races, primarily humans. Most tieflings have never even seen hell themselves.