Yes Vidiot it was normal to alter a new copy of any hand written text in your possession, the impulse would be irresistible if you thought you could improve it, why not since no scribe ever thought "I am writing a part of the Bible". All Bible texts are a selection by the Roman Church of earlier manuscripts to suit their political agenda.
Smiddy, there is some sort of logic that an almighty god would leave clear instructions but the premise is wrong since almighty gods are only beliefs in the first place and meaningful logic is only applied to fact. Nevertheless what heavenly father would leave such a rag-bag of illogical texts to confuse his children with--and then beat their brains out if they didn't get it right?
To get to the root of this religion business it is really about the putative authority of the preacher. I missed a few words out of my earlier post and had wanted to say: It would be a religious coup to claim that all other versions of holy texts were defective but only those in your possession were the true words of God and no doubt this trick was played on the peasants.
If you can show 'evidence' to be in possession of "holiness" or "Divine truth" you gain authority and make good money!
In the early British churches as elsewhere the key was all about how holy or effective your relics were and if they caused miracles. If your abbey had a holy object which won battles or cured the sick, people would flock to you and fill the coffers especially if it attracted royal patronage.
In a similar way the Watchtower org play their unscrupulous trump card by claiming not only their text but their interpretation of it is the "true religion". It's just a superstition, superstition and a misguided belief in holiness.