I tend to go with Hanlon's Razor with this type of thing. "Never attribute to malice that which is adequately explained by stupidity." Or, in this case, ignorance. The problem is that even when individuals are relieved of their ignorance, they often hold onto it because humans are terrible at letting go of their previously held beliefs. Folks don't want to think they may have been wrong. They'll think, sure, it may leave a bit of a rut, but it doesn't really matter.