In line with Doug's comments, the idea that redactions "corrupt" the Bible are the late invention of American Fundamentalism from the First and Second Awakenings. This idea is often called "radical Sola Scriptura" as it supplants the Bible as the revelation for Christianity.
For Christianity, the final revelation from G-d is the Person of Jesus Christ, not Scripture. Referred to as the Incarmate "Word" in John chapter 1, Christianity gave a qualifier to the Scripture canon, naming it the "written" Word of God by contrast.
Redactions and editorial processes make up the inspiration for traditional Christian denominations. But the radical departure which came from the period which birthed the JWs replaced Jesus with the Bible as the foundation for Christian religion. This required a new theology which states that the written word has to be inerrant and untouched since first inscribed. The reason is that the Book is seen as a direct revelation from G-d, and thus any changes to it would disqualify it as such.
The idea is very Gnostic, as Doug explains, as they believed holy writ was revelation and salvation possible only by learning the secrets hidden in the texts. Christianity rejected this notion, denying that reading Scrioture was a requisite to salvation.
If Scripture was a requisite to salvation as the Gnostics and their modern counterparts suggest then, yes, it stands to reason that only the first texts in the purest forms would be acceptable. But since the texts were written to be used as liturgical texts (most of which as sung or chanted to a meter that exists in the original language cadence in some instances), it stands to reason that the texts would be fitted for such cantor use.
The canonization of both Jewish and Christian Scripture was to authorize works for the Lectionary, not as a compendium of doctrine. It was designed to be read aloud as in synagogue and Eucharistic services, not rummaged through as the Gnostics claimed to search for life-saving codes that only a select could understand.