In fact the WTS teaches that the bible cannot be understood without their publications and explanations..........
The Watchtower, October 1, 1994, Page 8:
CHANNEL TO UNDERSTANDING THE BIBLE
JESUS assured us that after his death and resurrection, he would raise up a “faithful and discreet slave” that would serve as his channel of communication. (Matthew 24:45-47) The apostle Paul identified this channel to the Ephesian Christians when he wrote that “there might be made known through the congregation the greatly diversified wisdom of God, according to the eternal purpose that he formed in connection with the Christ, Jesus our Lord.” (Ephesians 3:10, 11) It was the congregation of anointed Christians, born at Pentecost 33 C.E., that was entrusted with the “things revealed.” (Deuteronomy 29:29) As a group, anointed Christians serve as the faithful and discreet slave. (Luke 12:42-44) Their appointed assignment from God is to provide spiritual understanding of the “things revealed.”
Even as Bible prophecy pointed forward to the Messiah, it also directs us to the close-knit body of anointed Christian Witnesses that now serve as the faithful and discreet slave. It helps us to understand the Word of God. All who want to understand the Bible should appreciate that the “greatly diversified wisdom of God” can become known only through Jehovah’s channel of communication, the faithful and discreet slave.—John 6:68.