Multiple good hypotheses here. I’d like to add my own. The governments can be viewed as a modern iterations of religious cults, and there is no bigger taboo in a religious organization than questioning the basic dogma.

Try to question democracy in a democratic republic and you immediately get the weird looks, and irrational dismissal. 9 times out of 10 this self preservation instinct is good and beneficial to everyone involved, because giving a benefit of doubt to closeted authoritarians would be a mistake. That one time somebody really wants to have an honest discussion, it simply sucks.