> nobody wants Nazis or Pedophiles to spread their opinions because they are obscene.

I want both sets of people to expose their views to the public. Disgusting though these views may be, it is safer for society if individuals are able to check and decide that someone else's views are reprehensible. If the people are merely told such by authorities, with the "offending" content immediately removed, then the authorities have enormous power to expand the definition of "offending" when it pleases them to do so.