Can someone explain to me why businesses might want employees to leave cameraphones at home?

I mean- WHY? What can they do with cameraphones that is so damaging? This article talks about "damaging spy shots that can reveal a companies trade secrets" - but is this really a risk? Only if these things are on the one hand not secret enough for someone to bother smuggling in a proper camera and doing the industrial espionage thing properly, yet at the same time secret enough to require protection?

What stops an employee just seeing something, remembering it, and telling the competition about it? Is the risk here that cameraphones might offer proof - or put another way, that what your employees might say is deniable until they have photos?

If you have an employee who wants to take your secrets to the competition, what additional danger does a cameraphone pose?