You realize the Deuterocanonical is included in both the Septuagint and every single edition of the Christian Bible prior to the 16th Century.
Why wouldn’t the admonition to ‘neither shall ye diminish ought from it?
Also, if you accept chapter 6... how do you deal with the protestant grumbling present throughout John 6:52-59?
Of course the first prophet Moses is and should be included in every Christian Bible. Christ had Moses and Elijah with Him on the mount of Transfiguration... ought to be a 'warning' to those that revised the Bible as to who Christ gave credibility.
I do not understand the question Why wouldn’t the admonition to ‘neither shall ye diminish ought from it?
Christ said warning even to us .... who would be sitting in the seat of Moses... Matthew 23: The 'religious' community.
I cannot worry about what other denominations grumble over. IITimothy 2:15 Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.
But shun profane and vain babblings: for they will increase unto more ungodliness.
I know for a fact Catholic doctrine considers much of what Moses penned as allegories and not still in effect. But Moses laid out in Deuteronomy what is required to be blessed and what to expect IF anyone/church claims they have and hold ownership to the Written Word.