At this point, I don't think anyone since Benjamin Winchester has caused more damage than Heimerdinger in terms of confusing people about the Book of Mormon. It's one thing for BYU scholars to debate which hill in Central America is the "true" Cumorah; hardly anyone reads their scholarly work. True, it filters out through official Church media, but at least the Church formally claims neutrality (in practical terms, the Church seems neutral only about where in Mesoamerica the Book of Mormon events took place).
But Heimerdinger has deeply influenced the youth of the Church through his book series. A million copies? Are there any youth in the church who have not read his books? That's a survey I'd like to see. In my informal surveys of kids I know, homes I've visited, etc., I'd say his work is ubiquitous.
No wonder so many youth leave the Church when they realize there is zero evidence in Mesoamerica for the Book of Mormon.
Here's a blog exchange (http://frostcave.blogspot.com/2013/11/the-latest-from-cumorahs-hill.html) that made me curious:
In addressing this matter one cannot ignore the fundamental reasons why the Heartland model is so attractive and will continue to cultivate advocates of the kind who approached me at Costco. These reasons go beyond scholarship. They are so powerful that they utterly stifle scholarship. At this year's BMAF Conference we listened to several presentations citing scholarly arguments against the "Heartland" platform. [I have critiqued these. They are attacking straw men, relying primarily on the discredited Times and Seasons articles and their various "adjustments" to the Book of Mormon text.] However, I promise you, with most adherents to the Heartland model, such arguments have no effect upon them whatsoever. The core philosophy is such that most Heartlanders would respond, "Who cares if the scholarship is presently flawed! The scholarship will improve. The core philosophy is the thing."
The motivations behind this movement may be diverse and difficult to sum up in a few words, but if pushed, the two that I would choose are the ones that appear in the title of this article: American Exceptionalism. [I'll have more to say on this in the future, but for now, think of the crowd to whom he was speaking and consider their agenda.]