When Montag visits Faber, Faber tells him various things about his own past life as a teacher, his fear and cowardice in not preventing the book ban, and his opinions on modern culture. One point he makes is how books are honest and tell the truth as seen by the writer, no matter how uncomfortable that might make others (a point made earlier by Beatty):
"So now do you see why books are hated and feared? They show the pores in the face of life. The comfortable people want only wax moon faces, poreless, hairless, expressionless."
(Bradbury, Fahrenheit 451, Google Books)
This is in stark contrast to the television walls, which are tailored for the user and only show what is comforting. When people are only exposed to what they want to see, they become insular and narrow-minded; the sheer amount of information in books guaranteed that people had a wide range of influences. Without books, people all speak the same way, like the same things, and express the same opinions.