The corrupting factor behind this is their arrogant belief that they're authorized to lie if it benefits them.
I had already been baptized for about a year when I learned of this doctrine. It came up during the Bible reading. We were assigned a few chapters from the book of Judges and the talk that week was about Rahab. The lesson the Watchtower took from it is that those who oppose Jehovah are not entitled to the truth. This is straight out of their literature.
Once I was out I learned that this idea had its origins during the Rutherford era and that back then it was called theocratic warfare. It's a corrupting influence because it gives them license to essentially lie whenever they think it's in the religion's best interests. After a while, it starts to corrode their core beliefs.