Sure, that might be good advice, but such absolutism isn't viable as a workplace system. Research into propinquity (http://en.wikipedia.org/wiki/Propinquity) tells us that romantic relationships are actually quite likely in the workplace. We should develop systems that handle this less-than-ideal(sometimes) behaviors. One of those systems is anti-discrimination law.
Smoking is forbidden on airplanes. But if someone does smoke, it's better that they have an ashtray available rather than starting a fire by trying to dispose of the ashes improperly.
