Smoking is an issur d’oreisa. The smoker is knowingly putting himself in a matzav of sakana for no reason other than his own fleeting pleasure. He’s also threatening the lives of those around him.
Facebook may be used to facilitate aveiros (as can cars, phones, grocery stores, etc.) but is also used for good by kiruv organizations and by families who use it to stay in touch. It is as clearly prohibited by all Orthodox poskim as smoking