There's an essay percolating in the back of my head on the theme of why radio is more powerful than television. In the mean time, let me argue by example.
Exhibit A: Bad science kills. From the early 20th century through roughly 1960 the psychology establishment viewed loving behaviour toward children as a problem. At one point the head of the American Psychological Association declared "When you are tempted to pet your child, remember that mother love is a dangerous instrument" and "there are serious rocks ahead for the over-kissed child" — and then defined over-kissing as kissing your child more than once a year. There were US Government pamphlets warning parents not to touch their children. "Never kiss a baby, especially on the mouth. Don't rock or play with children." In the 1940s health care workers (quoting now from the story linked below) "started noticing that some children in hospitals who were treated this way — never picked up, never loved — would wither and die. Literally die. But even this did not change the opinion of the psychological establishment."
For more on this, and some equally heartwrenching related stories, listen to the Unconditional Love episode of This American Life. I suggest keeping a box of kleenex close to hand.