Why do Mormon say that the Journal of Discourses (Brigham Young's sermons) is not LDS Doctrine?

First, I would like to point out that it is more than just Brigham Young's sermons in the Journal of Discourses.

That being said, even though the vast majority of the JoD is clearly aligned with LDS doctrine, it is not a definitive, authorized source for us. I can disregard the whole multi-volume set because we are not accountable for what's in there, no more than we are for the personal speculations of any other Church leader.

But I still don't think that answers your question. If you read the whole sermon in context, you would find that Brigham Young made it clear that his statement should not mean that anything he said was scripture, but only that which he had the opportunity to correct and send to the Saints as scripture. Further, President George Q.

Cannon explained that the scriptures (Bible, Book of Mormon, Doctrine and Covenants and Pearl of Great Price) are the only source of official doctrine, coupled with later revelation to the prophets that has been presented to the Church and sustained.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.