In the US 'the left' (and it's various offshoots) is pretty much a straight-line descendent of Puritanism, albeit stripped of it's direct religious motivation. So while the right may ban porn because 'evil woman parts leading us astray', the left will ban it because 'exploitative patriarchal degradation of women'. In reality they've just found a different rationalization for a cultural choice that was made when the Mayflower first dropped anchor.