It's pretty hard to convince people otherwise. One of the trainers at my barn has a TB mare who's 2 stalls down from a pony that cribs. Her horse recently found that she could pull on a loose piece of her feed tub and make a lot of noise; not cribbing, just playing with something with her mouth that makes a loud obnoxious sound. I overheard the trainer say that her horse better not be learning how to crib from the pony- mind you, her mare can't even see
the pony, so she'd have to learn just by hearing him grunt. When I commented that studies haven't shown any evidence that horses learn to crib from observing other horses do it, she just dismissed it because I have a horse who cribs, and therefore I must be biased.
It couldn't possibly be that I have a horse that cribs and therefore have a personal reason to really look into the latest research on causes, prevention and management of cribbers