Would you say the same about gambling software? What about software related to selling heroin?
All of these products are designed to be as addictive as possible (to varying degrees). The whole point of of an addiction is that your are there voluntarily. (Not saying facebook is as bad as the things above, just that they are all designed to addict.)
They certainly do make it as addictive as possible, but IMO that still does not mean users are there involuntarily. Persuasion is not the same as coercion.
All of these products are designed to be as addictive as possible (to varying degrees). The whole point of of an addiction is that your are there voluntarily. (Not saying facebook is as bad as the things above, just that they are all designed to addict.)