Well most of them live in a hegemonic cultural environment where civility is very important and the only challenges to their worldview they ever encounter are cherry picked rage bait from the Fash. They've mostly never even seriously critiqued their own views and beliefs, and have probably never been challenged in good faith and certainly not from the left. A lot of them just straight up have no experience in dealing with hostility or conflict regarding their beliefs so they default to civility policing and dismissal.