Pretty much the idea of more privacy. In my case I have the parking lot for a social organization behind me with a 4 foot cyclone fence. A side of the yard is one of their driveways to that parking lot with a 4 foot fence. To top it off the neighborhood kids, teens and adults will bicycle or walk their dogs up and down that drive and around the parking lot. The Michigan laws say that the plants are legal as long as they are not visible to the public under normal circumstances and not creating a nuisance. Not only are the flower gardens planned out but so is the vegetable garden.
Plus the plants have to be secured from minors and I doubt that a standard 4 foot cyclone fence would be considered secure
.Just about everything I do in that backyard is designed for privacy first and then distracting the view of people who might by walking by second. Another 5 to 10 years and the shrubs will be tall and wide enough to provide a living fence. Once that happens if someone wants to jump the fence and push their way though the shrubs they will quickly run into barberry shrubs.
Preventing people who walk by from noticing the plants means that they will not be telling their family or neighbors and possibly trickling down to some teenagers who have to prove that they can rip off anything.
great and maybe some day cannibis will be legal everywhere so we can all enjoy the absence of paranoia. 
