A sign on the doorway of a large local restaurant reads: "Do not enter here."
"Do not disconnect manually." How does someone remove the portable drive from the USB hub?
"Don't spend a lot of time on marketing proposals for existing clients unless they request one." Hmm. Does that mean I can prepare one if I think I can do it quickly?
We can all remember those childhood moments in the supermarket when our mom would rattle off a barrage of, "Don't touch that one!", "Don't talk to that stranger!", Don't eat that brand of peanuts!" (Fill in your favorite).
Humans are action-oriented creatures. You can tell them what not to do, but know this: If you don't tell them what to do, they will do something.
Are you willing to live with the results of their best guess?