Until a website you frequent gets marked as a "human trafficking hub", whatever that means.
Government has never used precedent that pornography filters set to expand the scope of filtering before [0] [3]. The government doesn't have incentive to block things that aren't 'obscene' [1] [2].
The warm fuzzies the idea of a wholesome internet limited to Facebook, World Net Daily and Veggie Tales videos, absent of bad ideas and hard truths, brings are too intoxicating.
[0] http://www.theinquirer.net/inquirer/news/2470767/uk-governme...
[1] https://www.privateinternetaccess.com/blog/2016/08/india-acc...
[2] https://www.theguardian.com/technology/2012/jan/22/sopa-pipa...
[3] https://en.wikipedia.org/wiki/Internet_censorship_in_the_Uni...