It's simple, bones - by keeping smokers on the quit, smoke, quit, smoke, quit, smoke rollercoaster - with healthy doses of guilt tossed in, the dollars keep rolling in to the big Pharma houses (NRT's and cessation drugs), Big Tobacco(smoke 'em if you got 'em), and the Gov't(tobacco taxes, anyone?).
PV's break the cycle, and end the ride, as do most other harm reduction products. Social engineering at its finest.