I don't think they are ignorant, at least the ones I have spoken to. I think they are comfortable with what they are doing and I know two that have given thought to various things that are mentioned by those that leave.
I didn't suddenly find out about 1975 when I left or what had been taught in early publications. I purchased old publications from book fairs in the early 1970's and I wasn't comfortable in the congregation with several different things. But I never thought of leaving.