I certainly agree with you DBMormon. While I, too, was aware of the many controversial areas of church teachings and history, what I knew mostly did not come from manuals and actual church teachings, but from looking at materials outside the church and from conversations with knowledgeable members. The conversations with knowledgeable members were rare and the information was generally apologetic, not necessarily accurate, and generally smacked of folklore. Some scant information, perhaps like the general idea that Joseph Smith practiced polygamy, was clearly available in manuals and if your teacher decided to make that part of the lesson you could learn about it - without things like polyandry, marrying other men's wives, and marrying 14-year-olds. Real, true information was available only to the select few who were permitted into the locked archives, and some of those who were bold enough to publish or teach some of that information that they had come across were excommunicated as heretics and apostates.
Let me propose one not uncommon scenario to you: A newly baptized sister is called to teach Primary soon after baptism (20 years ago there were not rules about attending SS class like there are now, but no difference, the stuff isn't in that manual). The idea of her teaching Primary is that she can learn the basics of the gospel while teaching the young children - makes perfect sense. Turns out she's really good at it and really likes it. She spends most of her 20 years in Primary as a teacher and eventually a leader, spending little time in adult classes and is a model member of the church. She holds a temple recommend, bears her testimony a few times a year, attends and helps out with activities, etc. She followed the warnings not to use outside materials in her lessons, and repeated that warning to teachers when she became a leader. Where, exactly, was she supposed to be exposed to information outside the Primary materials?
The assertion that people should have known actually tees me off.
The only way for the general go-with-the-flow member to know is if it is taught to them. I believe that is one of the purposes of the essays, yet even then so many are totally unaware of them and one has to know where to look to find them on the church site. "You should have known" is insulting BS.
In the absence of knowledge or faith there is always hope.
Once there was a gentile...who came before Hillel. He said "Convert me on the condition that you teach me the whole Torah while I stand on one foot." Hillel converted him, saying: That which is despicable to you, do not do to your fellow, this is the whole Torah, and the rest is commentary, go and learn it."