Mormon Doctrine

I was recently banned from r/lds because I said that the book Mormon doctrine isn’t doctrine. I said that it shouldn’t be referenced as doctrine and has many things in it that are incorrect.

Mormon doctrine was written by seventy Bruce r mcconckie without the approval or knowledge of the twelve nor the first presidency. Apostle mark e Peterson said it was “full of errors and misstatements, and it is most unfortunate that it has received such wide circulation”. Elder Peterson recommended over 1,000 corrections to the book. Mcconckie was actually asked by David o McKay to not reprint it at the time.

For example, in the original 1958 version, mcconckie said black people were literal descendants of Cain and their lineage was a result of them being “less valiant” in their premortal existence. This was corrected in later reprints. But the book still has never been considered official doctrine despite reprints.

I’m just confused as to why this is a controversial thing to say. I’ve always been taught that the book isn’t doctrine and shouldn’t be treated as such. Is this not a universally known thing in the church? Are there people that actually treat this book as doctrine? Or perhaps have just always assumed it was?