The angel made it clear to Nephi (and to us) that the corruptions of the Bible were not simply a result of subtle accidents of hand and eye, but rather a premeditated program with evil ends in mind; those involved in this abominable enterprise were a part of the mother of harlots and thus represented and accomplished the purposes of him who is Perdition.
Even in Jesus' day the desecration of the scriptures was under way. “Woe unto you, lawyers!” the Lord cried out, “for ye have taken away the key of knowledge, the fulness of the scriptures; ye enter not in yourselves into the kingdom; and those who were entering in, ye hindered” (JST, Luke 11:53; italics added).
“The devil wages war against the scriptures,”wrote Elder McConkie. “He hates them, perverts their plain meanings, and destroys them when he can. He entices those who heed his temptings to delete and discard to change and corrupt, to alter and amend, thus taking away the key which will aid in making men 'wise unto salvation' (2 Timothy 3:15-17).” (Doctrinal New Testament Commentary 1:624-25.)