Infallibility comments are questions or statements that sound as if the speaker believes s/he couldn’t possibly be wrong.
When people believe that a speaker is arrogant, “high and mighty” or believes in their own infallibility, there is a tendency to try and bring that person “down a peg”. They stop listening and gather their resources to attack the “perfect person”. People get this impression of self-infallibility in a number of ways. For example, “over-selling” an idea may give that impression.
That’s not to say that having confidence when one speaks is a bad thing. Confidence is good, but so is a demonstrated openness showing a) you aren’t perfect and b) you are willing to listen to others’ opinions and facts.