In verse 5, King Benjamin is speaking to his sons and referring to the plates of brass:
I say unto you, my sons, were it not for these things, which have been kept and preserved by the hand of God, that we might read and understand of his mysteries, and have his commandments always before our eyes, that even our fathers would have dwindled in unbelief, and we should have been like unto our brethren, the Lamanites, who know nothing concerning these things, or even do not believe them when they are taught them, because of the traditions of their fathers, which are not correct.
This is just as true for us today. If it were not for the records that were so carefully kept and preserved for us, we would not have the knowledge that we have now. We would have believed in traditions that were not correct because that was all we knew. What a wonderful thing that our Heavenly Father has taken such care to ensure that we could get these truths all these many years later!