Reddit changed it's own rules in order to narrow the scope of "acceptable political debate".

Some of you may recall that after the big exodus from Daily Kos following the Ides fo March decree, a subreddit called Kossacks_For_Sanders was created by a number of former prominent Bernie supporters. Over time, as other Sanders' subreddits have imploded due to subversion or infiltration by Clinton operatives, many people saw K4S as their refuge. There, topics were generally not censored (I say generally because in fact, some were).