One random link I followed from the Wikipedia article is the source for the statement "Europe has the highest number of sex slaves per capita in the world". http://realstars.eu/for-fair-sex/ The page prominently advocates for the Nordic model.
There is a substantial political movement, that crosses the feminist left to the paternalistic right, that holds that all prostitution is in some manner coerced and is a subset of sex trafficking, and this group is part of the core if support for every anti-sex-trafficking law, and even moreso for laws like the proposed one that strip well-established protection and target people who aren't sex traffickers for some conduct several steps removed from trafficking.
While trafficking is a real problem that needs to be combatted, it's also the new banner under which the movement seeking ever more radical legislation to combat the existence of sex work is marching.