People don't typically try to tell you about the salt on crackers or the color of the sidewalk. They're generally telling you highlights and to dismiss their attempt to share what they consider to be significant with you is the same thing as judging their ability to determine what is and what is not significant. Most people are not good judges of what is significant. Bear in mind people took experimental gene therapy shots for free donuts.
If someone tells me something is significant, I will give them the benefit of the doubt and do some initial exploration of that thing.
It starts to become a problem when we incorporate timelines into play. If it is something I've already explored, they wouldn't know that I've already explored it so, even though I might know that my dismissal is not prejudicial, the other party does not know that. All they experience is rejection.
Such a person might be prone to falsely equate what they experienced with willful ignorance on my part, however their accusation is based upon ignorant assumptions.
Speaking from my perspective, I've canvassed a LOT of people on the subjects I talk about. Almost nobody has ever heard of these topics. This means they are not in the position I described above where they've already studied this thing I'm showing them and have the ability to intelligently converse upon that subject and countervail any arguments for that thing's significance. So when they dismiss these things, they are dismissing them out of ignorance.